• HVYRAIN: Nws Weather Prediction Center College Park Md

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Nov 2 15:23:50 2021
    This is a multi-part message in MIME format...

    ------------=_1635866695-2133-5083
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 021523
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1122 AM EDT Tue Nov 02 2021

    Day 1
    Valid 16Z Tue Nov 02 2021 - 12Z Wed Nov 03 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    16z update:
    No signficant changes were required for excessive categories after
    reviewing 12z CAMS/HREF and early global guidance.

    Gallina

    ...South Florida...
    Some moisture return from the Atlantic along with slowly
    increasing MU CAPE is expected to move ashore
    Miami-Dade/Broward/Palm Beach counties.

    Precipitable water values, on the heels of weak low-level return
    flow from the warm Gulf Stream, are expected to creep up to ~1.5",
    and some effective bulk shear of 25 kts lurks nearby across the
    southeast Gulf of Mexico, which has trended slightly upward
    lately, induced by a shortwave edging eastward through the FL
    Panhandle. The Gold Coast has seen 150-300% of their usual two
    week precipitation, so the Dry Season has not been as dry as usual
    in late October. While local amounts of 3"+ falling at 1.5"+ an
    hour rates is non-zero near the coasts of Miami-Dade, Broward, and
    Palm Beach counties, it does not appear high enough due to
    differing model ideas across the area for a Marginal Risk at this
    time.

    ...Texas...
    Convection is firing up across the South Plains in proximity to a
    surface low and associated front stretching from the Southern
    Plains to the Gulf Coast. With moisture convergence expected to
    persist over central Texas and CAPE values approaching 1000J/kg
    during the afternoon/evening, this environment may be conducive
    for hourly rainfall rates up to 0.50 inch/year. There may be very
    isolated that may get over 2 inches of rain, but in general, most
    locations will likely remain less than 1.5 inches. The better forcing/instability looks to hold off until day 2.


    Campbell/Roth


    Day 2
    Valid 12Z Wed Nov 03 2021 - 12Z Thu Nov 04 2021

    ...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL OVER PORTIONS
    OF TEXAS...

    Shortwave energy moving across the Southern/Central Rockies will
    eject out into the Plains during this period, pushing the surface
    front and the precipitation footprint south. CAPE values of
    500-1200 J/Kg will be present across much of the southern half of
    the state; which will aid in developing/maintaining scattered to
    widespread convection. It will also help support hourly rainfall
    rates of 0.50 to 1.50+ inch/hour. Although there is still some
    spread with the placement of the QPF maximums, 1 to 3 inches are
    expected from South Texas to the Texas/Louisiana border. The
    latest WPC QPF trended to having more QPF over South Texas and
    central portions of the state, which was a westward trend. The
    Marginal Risk area for excessive rainfall was expanded to reflect
    this change. These amounts may lead to local flash flooding.

    Campbell

    Day 3
    Valid 12Z Thu Nov 04 2021 - 12Z Fri Nov 05 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Campbell


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!staMWrsF4CoG7aRDUrLCuMj2m5TDk8sqDxcs7Cni49xa= q-KriWxD0bLWxBGKQBq1KjrX0kzJ$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!staMWrsF4CoG7aRDUrLCuMj2m5TDk8sqDxcs7Cni49xa= q-KriWxD0bLWxBGKQBq1KlNJYpS9$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!staMWrsF4CoG7aRDUrLCuMj2m5TDk8sqDxcs7Cni49xa= q-KriWxD0bLWxBGKQBq1KqMWSuQH$=20


    $$




    ------------=_1635866695-2133-5083
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1635866695-2133-5083--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Nov 2 19:31:26 2021
    This is a multi-part message in MIME format...

    ------------=_1635881490-2133-5135
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 021931
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    330 PM EDT Tue Nov 02 2021

    Day 1
    Valid 16Z Tue Nov 02 2021 - 12Z Wed Nov 03 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    16z update:
    No signficant changes were required for excessive categories after
    reviewing 12z CAMS/HREF and early global guidance.

    Gallina

    ...South Florida...
    Some moisture return from the Atlantic along with slowly
    increasing MU CAPE is expected to move ashore
    Miami-Dade/Broward/Palm Beach counties.

    Precipitable water values, on the heels of weak low-level return
    flow from the warm Gulf Stream, are expected to creep up to ~1.5",
    and some effective bulk shear of 25 kts lurks nearby across the
    southeast Gulf of Mexico, which has trended slightly upward
    lately, induced by a shortwave edging eastward through the FL
    Panhandle. The Gold Coast has seen 150-300% of their usual two
    week precipitation, so the Dry Season has not been as dry as usual
    in late October. While local amounts of 3"+ falling at 1.5"+ an
    hour rates is non-zero near the coasts of Miami-Dade, Broward, and
    Palm Beach counties, it does not appear high enough due to
    differing model ideas across the area for a Marginal Risk at this
    time.

    ...Texas...
    Convection is firing up across the South Plains in proximity to a
    surface low and associated front stretching from the Southern
    Plains to the Gulf Coast. With moisture convergence expected to
    persist over central Texas and CAPE values approaching 1000J/kg
    during the afternoon/evening, this environment may be conducive
    for hourly rainfall rates up to 0.50 inch/year. There may be very
    isolated that may get over 2 inches of rain, but in general, most
    locations will likely remain less than 1.5 inches. The better forcing/instability looks to hold off until day 2.


    Campbell/Roth


    Day 2
    Valid 12Z Wed Nov 03 2021 - 12Z Thu Nov 04 2021

    ...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL OVER PORTIONS
    OF TEXAS...

    20z update:
    ...Texas...
    12z guidance continues to trend slightly faster initially with the
    southward push of the cold front across north-central Texas,
    reducing the potential for overlapping surface based convection
    and deeper mid-level ascent northward of the boundary. The HREF
    probabilities and QPF totals have seen a noted decrease in
    probability and coverage of hourly rates over 1" through the
    morning/early afternoon hours and so the Marginal Risk has been
    trimmed slightly southward. However, return moisture off the
    western Gulf will increase instability through the afternoon
    increasing the potential for surface based convection by early
    evening, both across eastern TX as well across south Texas into
    the Rio Grande Valley. The front will slow slightly and with
    increased convergence will likely enhance thunderstorm risk.=20
    Rates of 1.5-2"/hr increase across the Texas Hill Country toward
    Houston Metro by late evening enough to maintain a Marginal Risk,
    particularly given soils are a bit more saturated recently per
    AHPS anomalies.

    Into the evening and overnight hours, Hi-Res CAMs further expand
    thunderstorm development across South-Central to southern Texas
    with greatest probabilities near Corpus Christi though, areas
    further west across the Brush country of South Texas will have
    isolated potential of rates in excess of 2"/hr and isolated totals
    up to 4" suggesting further expansion of the Marginal Risk area
    toward the south even with higher FFG/drier ground conditions.

    Gallina


    ...Texas...
    Shortwave energy moving across the Southern/Central Rockies will
    eject out into the Plains during this period, pushing the surface
    front and the precipitation footprint south. CAPE values of
    500-1200 J/Kg will be present across much of the southern half of
    the state; which will aid in developing/maintaining scattered to
    widespread convection. It will also help support hourly rainfall
    rates of 0.50 to 1.50+ inch/hour. Although there is still some
    spread with the placement of the QPF maximums, 1 to 3 inches are
    expected from South Texas to the Texas/Louisiana border. The
    latest WPC QPF trended to having more QPF over South Texas and
    central portions of the state, which was a westward trend. The
    Marginal Risk area for excessive rainfall was expanded to reflect
    this change. These amounts may lead to local flash flooding.

    Campbell

    Day 3

    The Day 3 outlook will be updated by 2030Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!ufyw0UQxmQXnITsJfqS0Ge9mCRaXgFDRSYNlMJ9RBk75= 44bdD52avruNPfE4cTvjOP1cUIEs$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!ufyw0UQxmQXnITsJfqS0Ge9mCRaXgFDRSYNlMJ9RBk75= 44bdD52avruNPfE4cTvjON9vM3hU$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!ufyw0UQxmQXnITsJfqS0Ge9mCRaXgFDRSYNlMJ9RBk75= 44bdD52avruNPfE4cTvjOIZC5DpP$=20


    $$




    ------------=_1635881490-2133-5135
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1635881490-2133-5135--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Nov 2 19:31:52 2021
    This is a multi-part message in MIME format...

    ------------=_1635881516-2133-5136
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 021931
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    331 PM EDT Tue Nov 02 2021

    Day 1
    Valid 16Z Tue Nov 02 2021 - 12Z Wed Nov 03 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    16z update:
    No signficant changes were required for excessive categories after
    reviewing 12z CAMS/HREF and early global guidance.

    Gallina

    ...South Florida...
    Some moisture return from the Atlantic along with slowly
    increasing MU CAPE is expected to move ashore
    Miami-Dade/Broward/Palm Beach counties.

    Precipitable water values, on the heels of weak low-level return
    flow from the warm Gulf Stream, are expected to creep up to ~1.5",
    and some effective bulk shear of 25 kts lurks nearby across the
    southeast Gulf of Mexico, which has trended slightly upward
    lately, induced by a shortwave edging eastward through the FL
    Panhandle. The Gold Coast has seen 150-300% of their usual two
    week precipitation, so the Dry Season has not been as dry as usual
    in late October. While local amounts of 3"+ falling at 1.5"+ an
    hour rates is non-zero near the coasts of Miami-Dade, Broward, and
    Palm Beach counties, it does not appear high enough due to
    differing model ideas across the area for a Marginal Risk at this
    time.

    ...Texas...
    Convection is firing up across the South Plains in proximity to a
    surface low and associated front stretching from the Southern
    Plains to the Gulf Coast. With moisture convergence expected to
    persist over central Texas and CAPE values approaching 1000J/kg
    during the afternoon/evening, this environment may be conducive
    for hourly rainfall rates up to 0.50 inch/year. There may be very
    isolated that may get over 2 inches of rain, but in general, most
    locations will likely remain less than 1.5 inches. The better forcing/instability looks to hold off until day 2.


    Campbell/Roth


    Day 2
    Valid 12Z Wed Nov 03 2021 - 12Z Thu Nov 04 2021

    ...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL OVER PORTIONS
    OF TEXAS...

    20z update:
    ...Texas...
    12z guidance continues to trend slightly faster initially with the
    southward push of the cold front across north-central Texas,
    reducing the potential for overlapping surface based convection
    and deeper mid-level ascent northward of the boundary. The HREF
    probabilities and QPF totals have seen a noted decrease in
    probability and coverage of hourly rates over 1" through the
    morning/early afternoon hours and so the Marginal Risk has been
    trimmed slightly southward. However, return moisture off the
    western Gulf will increase instability through the afternoon
    increasing the potential for surface based convection by early
    evening, both across eastern TX as well across south Texas into
    the Rio Grande Valley. The front will slow slightly and with
    increased convergence will likely enhance thunderstorm risk.=20
    Rates of 1.5-2"/hr increase across the Texas Hill Country toward
    Houston Metro by late evening enough to maintain a Marginal Risk,
    particularly given soils are a bit more saturated recently per
    AHPS anomalies.

    Into the evening and overnight hours, Hi-Res CAMs further expand
    thunderstorm development across South-Central to southern Texas
    with greatest probabilities near Corpus Christi though, areas
    further west across the Brush country of South Texas will have
    isolated potential of rates in excess of 2"/hr and isolated totals
    up to 4" suggesting further expansion of the Marginal Risk area
    toward the south even with higher FFG/drier ground conditions.

    Gallina


    ...Texas...
    Shortwave energy moving across the Southern/Central Rockies will
    eject out into the Plains during this period, pushing the surface
    front and the precipitation footprint south. CAPE values of
    500-1200 J/Kg will be present across much of the southern half of
    the state; which will aid in developing/maintaining scattered to
    widespread convection. It will also help support hourly rainfall
    rates of 0.50 to 1.50+ inch/hour. Although there is still some
    spread with the placement of the QPF maximums, 1 to 3 inches are
    expected from South Texas to the Texas/Louisiana border. The
    latest WPC QPF trended to having more QPF over South Texas and
    central portions of the state, which was a westward trend. The
    Marginal Risk area for excessive rainfall was expanded to reflect
    this change. These amounts may lead to local flash flooding.

    Campbell

    Day 3
    Valid 12Z Thu Nov 04 2021 - 12Z Fri Nov 05 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Gallina


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!qj6rJPEImw6ItoNMVff949sOSZAtBzA_6P8pA_sHn0Pl= U2JizWeK5uIMwa7MpZ2ICHmk1UKV$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!qj6rJPEImw6ItoNMVff949sOSZAtBzA_6P8pA_sHn0Pl= U2JizWeK5uIMwa7MpZ2ICPDu1cFM$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!qj6rJPEImw6ItoNMVff949sOSZAtBzA_6P8pA_sHn0Pl= U2JizWeK5uIMwa7MpZ2ICMXvGJXD$=20


    $$




    ------------=_1635881516-2133-5136
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1635881516-2133-5136--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Nov 12 15:31:30 2021
    This is a multi-part message in MIME format...

    ------------=_1636731096-129950-3012
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 121531
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1030 AM EST Fri Nov 12 2021

    Day 1
    Valid 16Z Fri Nov 12 2021 - 12Z Sat Nov 13 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
    OF THE NORTHWEST AND NORTHEAST...

    16z update: Across the Northwest no substantive changes were made
    to the Marginal Risk area provided trends in remote sensing and
    observational data, as well as newer 12z Hi-Res CAM guidance and
    HREF probabilities remain on track for placement and forecast
    reasoning.

    For the Northeast, small adjustments to the western boundary were
    made based on RADAR trends and recent Mesoscale Precipitation
    Discussion 1127 issued at 1445z. IVT values remain in the 1000
    kg/m/s^2 range which is the 99th percentile for this time of year,
    given ample confluent moisture streams and PWs of 1-1.3" (95th
    percentile) for New England.=20=20

    Gallina

    ...Northwest...
    The atmospheric river event from Thu-Thu night will start to wind
    down this morning, with lingering impacts expected across portions
    of the Coastal Range and Cascades. As is typically the case,
    strong convergence zones will likely develop despite much of the
    energy starting to translate east, out of the region. This could
    lead to periods of heavy rain through Friday afternoon. For this
    reason, hourly rain rates could still be as high as 0.50-0.75
    inches through the first half of the forecast period with areal
    average precipitation totals of 1-2+ inches within 12 hours. As a
    result, flooding issues may continue, especially across the steep
    terrain and any burn scar areas in the Cascades over southwest WA
    and northwest OR. Therefore, a Marginal Risk area continues over
    these areas.

    Farther east today, the main deep-layer WAA/moisture surge
    (positive PW and 850-700 moisture flux anomaly) along the upper
    level jet axis will shift eastward into across the northern Great
    Basin and into the western slopes of the northern Rockies. PW
    values of 0.75-1.00" are around 3 standard deviations above normal
    per the GEFS/SREF, as is the 850-700 mb moisture flux anomalies
    with the uptick in SW-WSW flow. The lack of instability will
    likely cap hourly rainfall rates under 0.50". However, 3-hourly
    rates between 0.75-1.0" in spots may cause localized runoff issues
    given the current FFG, especially over isolated burn scar areas.

    ...Northeast...
    As the main low pressure area continues to deepen/occlude over the
    Upper Midwest-Great Lakes, a secondary low will develop along the
    main baroclinic zone (triple point) and track across NY and New
    England. Robust southerly low-level inflow (50-60kts at 850 mb or
    ~5 standard deviations above normal per the GEFS/SREF) will allow
    for a precipitous increase in moisture flux today ahead of the
    cold front, with PWs peaking around 1.25-1.40". The lack of
    deep-layer instability (MUCAPEs 100-250 J/kg) will limit the
    short-term rainfall rates over this region as well. However, with
    the bulk of the rain expected to fall in less than 6 hours, spotty
    areas of 1.5-2.0" within 3 hours per the high-res CAMs may lead to
    isolated runoff issues given the latest FFG -- especially along
    Downeast ME given the heavy rainfall over a week ago (where 14 day
    rainfall averages between 150-200% of normal).

    Hurley


    Day 2
    Valid 12Z Sat Nov 13 2021 - 12Z Sun Nov 14 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Hurley

    Day 3
    Valid 12Z Sun Nov 14 2021 - 12Z Mon Nov 15 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
    OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    A shortwave trough over the Gulf of Alaska early on Sunday will
    pivot eastward and reach the Pacific NW coast on Monday. During
    the intervening period, an initial surge of deep-layer
    WAA/isentropic ascent and moisture transport ahead of the warm
    front will push into western WA-OR Saturday night. The main
    Atmospheric River meanwhile will be directed into Vancouver Island
    by the start of Day 3 (12Z Sunday), then slowly drop southward
    across the Olympic Peninsula and northern WA Cascades Sun-Sun
    night ahead of the shortwave trough and associated surface cold
    front. Per the CW3E AR Scale, the GEFS and ECWMF are both
    indicating a moderate to strong Atmospheric River with a peak
    forecast AR rating of 4 on a 5-point scale. Integrated water vapor
    transport or IVT values peak between 750-800 kg/m/s during day 3,
    with PW values topping out aoa 1.25" along the coast. Per the 00Z
    GEFS...SW-WSW flow of 45-55+ kts within the 850-700 mb layer will
    lead to moisture flux anomalies of 3-3.5 standard deviations above
    normal. As with the departing AR, deep-layer instability will be
    scant -- generally 100-250 J/kg tops. However, considering the
    aforementioned factors along with the strong upslope component,
    pockets with with 1hr (3hr) rainfall rates of at least 0.50"
    (1.00") are anticipated, with 24hr total rainfall between
    2.5-5.0". Considering the current soil moisture and streamflow
    trends per the latest FLASH and SPoRT analyses, this next AR
    Sun-sun night could certainly cause additional short-term runoff
    issues.

    Hurley



    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!seGD1gtPBdx9wyLaXSq__fcXzhzT2dJUhTqoZbWGfPZu= K5d02R0n9kcSCyW2W4YR1hQY7r2W$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!seGD1gtPBdx9wyLaXSq__fcXzhzT2dJUhTqoZbWGfPZu= K5d02R0n9kcSCyW2W4YR1v7qzhaT$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!seGD1gtPBdx9wyLaXSq__fcXzhzT2dJUhTqoZbWGfPZu= K5d02R0n9kcSCyW2W4YR1tOBzEAj$=20


    $$




    ------------=_1636731096-129950-3012
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636731096-129950-3012--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Nov 12 19:41:30 2021
    This is a multi-part message in MIME format...

    ------------=_1636746094-129950-3148
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 121941
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    240 PM EST Fri Nov 12 2021

    Day 1
    Valid 16Z Fri Nov 12 2021 - 12Z Sat Nov 13 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
    OF THE NORTHWEST AND NORTHEAST...

    16z update: Across the Northwest no substantive changes were made
    to the Marginal Risk area provided trends in remote sensing and
    observational data, as well as newer 12z Hi-Res CAM guidance and
    HREF probabilities remain on track for placement and forecast
    reasoning.

    For the Northeast, small adjustments to the western boundary were
    made based on RADAR trends and recent Mesoscale Precipitation
    Discussion 1127 issued at 1445z. IVT values remain in the 1000
    kg/m/s^2 range which is the 99th percentile for this time of year,
    given ample confluent moisture streams and PWs of 1-1.3" (95th
    percentile) for New England.=20=20

    Gallina

    ...Northwest...
    The atmospheric river event from Thu-Thu night will start to wind
    down this morning, with lingering impacts expected across portions
    of the Coastal Range and Cascades. As is typically the case,
    strong convergence zones will likely develop despite much of the
    energy starting to translate east, out of the region. This could
    lead to periods of heavy rain through Friday afternoon. For this
    reason, hourly rain rates could still be as high as 0.50-0.75
    inches through the first half of the forecast period with areal
    average precipitation totals of 1-2+ inches within 12 hours. As a
    result, flooding issues may continue, especially across the steep
    terrain and any burn scar areas in the Cascades over southwest WA
    and northwest OR. Therefore, a Marginal Risk area continues over
    these areas.

    Farther east today, the main deep-layer WAA/moisture surge
    (positive PW and 850-700 moisture flux anomaly) along the upper
    level jet axis will shift eastward into across the northern Great
    Basin and into the western slopes of the northern Rockies. PW
    values of 0.75-1.00" are around 3 standard deviations above normal
    per the GEFS/SREF, as is the 850-700 mb moisture flux anomalies
    with the uptick in SW-WSW flow. The lack of instability will
    likely cap hourly rainfall rates under 0.50". However, 3-hourly
    rates between 0.75-1.0" in spots may cause localized runoff issues
    given the current FFG, especially over isolated burn scar areas.

    ...Northeast...
    As the main low pressure area continues to deepen/occlude over the
    Upper Midwest-Great Lakes, a secondary low will develop along the
    main baroclinic zone (triple point) and track across NY and New
    England. Robust southerly low-level inflow (50-60kts at 850 mb or
    ~5 standard deviations above normal per the GEFS/SREF) will allow
    for a precipitous increase in moisture flux today ahead of the
    cold front, with PWs peaking around 1.25-1.40". The lack of
    deep-layer instability (MUCAPEs 100-250 J/kg) will limit the
    short-term rainfall rates over this region as well. However, with
    the bulk of the rain expected to fall in less than 6 hours, spotty
    areas of 1.5-2.0" within 3 hours per the high-res CAMs may lead to
    isolated runoff issues given the latest FFG -- especially along
    Downeast ME given the heavy rainfall over a week ago (where 14 day
    rainfall averages between 150-200% of normal).

    Hurley


    Day 2
    Valid 12Z Sat Nov 13 2021 - 12Z Sun Nov 14 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
    OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    A broad area of subtropical moisture and warming will in place
    across the northeast Pacific Ocean, a subtle shortwave emerging
    from the sub-tropics will amplify along a tightening height
    gradient along the southeast periphery of the larger scale Gulf of
    Alaska closed low. This wave will quickly amplify, corral the
    enhance moisture and strengthen/tighten a warm front that extends
    eastward toward the Pacific Northwest. Total PWats of 1.25-1.6"
    will pool along the front with 65-70kt southwesterly jet enhancing
    the strong WAA along and ahead of the boundary into the Olympic
    Peninsula toward 00-03z Sunday. This WAA and ample moisture is
    about 2.25-2.75 Standard Anomalies or 99th percentiles, combined
    with strength of flux (60-70kts) in the 850-7H layer, supports IVT
    values in excess of 800 kg/m/s . Limiting factor is going to be
    duration of this event, as the warm front and associated WAA peaks
    about 06z but reduces quickly toward 12z even into the northern
    Cascades. With that stated, 12z Hi-Res CAMs particularly the ARW
    solutions, suggest hourly rates in excess of .5"/hr and 1.5-3"
    totals by 12z. Given 0-40cm soil saturation values are nearly
    100% per NASA SPoRT LIS anomaly products this should result in
    nearly all rainfall running off increasing rapid onset flooding
    risk. Freezing levels will initially be at or just below the
    higher peaks level (mainly in the Cascades), the strength of the
    WAA, coupled with rainfall could also quickly convert any of the
    snow to runoff as well. As such and in coordination with local
    forecast office in Seattle, a Marginal Risk of Excessive Rainfall
    has been introduced for the day 2 period, but particularly after
    14.00z Saturday evening into Sunday morning for the Olympic Range
    and Northern Cascade range of Washington.

    Gallina

    Day 3

    The Day 3 outlook will be updated by 2030Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!pObybZOCHYz3qVCOFvLLgFEpD5t__2rz-5-3FEDmc7C7= -R8CBRnXdZ0qP8jQm-yzORXgn73x$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!pObybZOCHYz3qVCOFvLLgFEpD5t__2rz-5-3FEDmc7C7= -R8CBRnXdZ0qP8jQm-yzOUvQrBBM$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!pObybZOCHYz3qVCOFvLLgFEpD5t__2rz-5-3FEDmc7C7= -R8CBRnXdZ0qP8jQm-yzOSdzjy7a$=20


    $$




    ------------=_1636746094-129950-3148
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636746094-129950-3148--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Nov 12 19:42:00 2021
    This is a multi-part message in MIME format...

    ------------=_1636746125-129950-3149
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 121941
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    240 PM EST Fri Nov 12 2021

    Day 1
    Valid 16Z Fri Nov 12 2021 - 12Z Sat Nov 13 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
    OF THE NORTHWEST AND NORTHEAST...

    16z update: Across the Northwest no substantive changes were made
    to the Marginal Risk area provided trends in remote sensing and
    observational data, as well as newer 12z Hi-Res CAM guidance and
    HREF probabilities remain on track for placement and forecast
    reasoning.

    For the Northeast, small adjustments to the western boundary were
    made based on RADAR trends and recent Mesoscale Precipitation
    Discussion 1127 issued at 1445z. IVT values remain in the 1000
    kg/m/s^2 range which is the 99th percentile for this time of year,
    given ample confluent moisture streams and PWs of 1-1.3" (95th
    percentile) for New England.=20=20

    Gallina

    ...Northwest...
    The atmospheric river event from Thu-Thu night will start to wind
    down this morning, with lingering impacts expected across portions
    of the Coastal Range and Cascades. As is typically the case,
    strong convergence zones will likely develop despite much of the
    energy starting to translate east, out of the region. This could
    lead to periods of heavy rain through Friday afternoon. For this
    reason, hourly rain rates could still be as high as 0.50-0.75
    inches through the first half of the forecast period with areal
    average precipitation totals of 1-2+ inches within 12 hours. As a
    result, flooding issues may continue, especially across the steep
    terrain and any burn scar areas in the Cascades over southwest WA
    and northwest OR. Therefore, a Marginal Risk area continues over
    these areas.

    Farther east today, the main deep-layer WAA/moisture surge
    (positive PW and 850-700 moisture flux anomaly) along the upper
    level jet axis will shift eastward into across the northern Great
    Basin and into the western slopes of the northern Rockies. PW
    values of 0.75-1.00" are around 3 standard deviations above normal
    per the GEFS/SREF, as is the 850-700 mb moisture flux anomalies
    with the uptick in SW-WSW flow. The lack of instability will
    likely cap hourly rainfall rates under 0.50". However, 3-hourly
    rates between 0.75-1.0" in spots may cause localized runoff issues
    given the current FFG, especially over isolated burn scar areas.

    ...Northeast...
    As the main low pressure area continues to deepen/occlude over the
    Upper Midwest-Great Lakes, a secondary low will develop along the
    main baroclinic zone (triple point) and track across NY and New
    England. Robust southerly low-level inflow (50-60kts at 850 mb or
    ~5 standard deviations above normal per the GEFS/SREF) will allow
    for a precipitous increase in moisture flux today ahead of the
    cold front, with PWs peaking around 1.25-1.40". The lack of
    deep-layer instability (MUCAPEs 100-250 J/kg) will limit the
    short-term rainfall rates over this region as well. However, with
    the bulk of the rain expected to fall in less than 6 hours, spotty
    areas of 1.5-2.0" within 3 hours per the high-res CAMs may lead to
    isolated runoff issues given the latest FFG -- especially along
    Downeast ME given the heavy rainfall over a week ago (where 14 day
    rainfall averages between 150-200% of normal).

    Hurley


    Day 2
    Valid 12Z Sat Nov 13 2021 - 12Z Sun Nov 14 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
    OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    A broad area of subtropical moisture and warming will in place
    across the northeast Pacific Ocean, a subtle shortwave emerging
    from the sub-tropics will amplify along a tightening height
    gradient along the southeast periphery of the larger scale Gulf of
    Alaska closed low. This wave will quickly amplify, corral the
    enhance moisture and strengthen/tighten a warm front that extends
    eastward toward the Pacific Northwest. Total PWats of 1.25-1.6"
    will pool along the front with 65-70kt southwesterly jet enhancing
    the strong WAA along and ahead of the boundary into the Olympic
    Peninsula toward 00-03z Sunday. This WAA and ample moisture is
    about 2.25-2.75 Standard Anomalies or 99th percentiles, combined
    with strength of flux (60-70kts) in the 850-7H layer, supports IVT
    values in excess of 800 kg/m/s . Limiting factor is going to be
    duration of this event, as the warm front and associated WAA peaks
    about 06z but reduces quickly toward 12z even into the northern
    Cascades. With that stated, 12z Hi-Res CAMs particularly the ARW
    solutions, suggest hourly rates in excess of .5"/hr and 1.5-3"
    totals by 12z. Given 0-40cm soil saturation values are nearly
    100% per NASA SPoRT LIS anomaly products this should result in
    nearly all rainfall running off increasing rapid onset flooding
    risk. Freezing levels will initially be at or just below the
    higher peaks level (mainly in the Cascades), the strength of the
    WAA, coupled with rainfall could also quickly convert any of the
    snow to runoff as well. As such and in coordination with local
    forecast office in Seattle, a Marginal Risk of Excessive Rainfall
    has been introduced for the day 2 period, but particularly after
    14.00z Saturday evening into Sunday morning for the Olympic Range
    and Northern Cascade range of Washington.

    Gallina

    Day 3
    Valid 12Z Sun Nov 14 2021 - 12Z Mon Nov 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE OLYMPIC
    PENINSULA AND NORTHERN WASHINGTON CASCADES...

    After the initial moisture surge with the warm front early Sunday
    morning, there may be some residual enhanced convergence lingering
    through the northern Washington Cascades at the start of the Day 3
    forecast time period (14.12z). Synopically, the leading shortwave
    will remain focused making landfall into central BC by early
    morning Sunday, while the upstream larger scale closed low
    descends in latitude toward the southeast. As such the
    subtropical moisture plume will once again narrow and focus north
    of the U.S. boarder into Vancouver Island. Southwesterly onshore
    flow at 25-30kts will keep modest ascent and moisture convergence
    for lighter showers across the Olympic Peninsula into the Northern
    Cascades with freezing levels rising above all but the most
    extreme peaks.=20

    There has been some uncertainty to the timing of the shortwave and
    therefore the placement and southward push of the frontal zone by
    early afternoon into overnight hours. Current trends suggest
    increasing confidence toward the boundary sliding south into
    western Washington before stalling ahead of the further upstream
    larger scale height-falls. Solid moisture convergence along the
    frontal zone accompanied by 1-1.25" Total PWat Values support a
    longer duration moderate to heavy rainfall event to start
    unfolding throughout the day, strengthening with lower level flow
    and increased moisture to 1.25-1.4" by overnight to 15.12z on
    Monday. The 12z GFS/ECMWF/CMC solutions suggest similar
    orientation and placement of the frontal zone across the Olympic
    Range and across into the northern Washington Cascades with 24hr
    totals of 4-7" and 3-6",respectively. Unlike on Day 2, the
    overall strength of flow (30-40kts at 85H) and depth of moisture
    support generally a magnitude lower in intensity given IVT values
    in the 300 to 400 range perhaps peaking near 600-700 kg/m/s toward
    15.12z but it is the length of duration, at 12-18 hour with
    nearly stationary or very slow southward progression of the
    boundary that is fairly orthogonal to the coastal ranges supports
    a increase of category to a Slight Risk of Excessive Rainfall.=20
    Colorado State ERO first guess suggests 20-35% probability to
    1-2yr ARI exceedance, which appears to correlate well with a high
    end Slight Risk area providing further confidence in this upgrade.
    =20=20

    Gallina



    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!sfddVhbI6eXcfMbFqltpvlG1aizugG-1ecigL8EvBy-c= jhvJLPVhL4MQCCt_GuwCfjge7kAy$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!sfddVhbI6eXcfMbFqltpvlG1aizugG-1ecigL8EvBy-c= jhvJLPVhL4MQCCt_GuwCfk3A5PXQ$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!sfddVhbI6eXcfMbFqltpvlG1aizugG-1ecigL8EvBy-c= jhvJLPVhL4MQCCt_GuwCfiSv5hxc$=20


    $$




    ------------=_1636746125-129950-3149
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636746125-129950-3149--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Nov 13 15:33:13 2021
    This is a multi-part message in MIME format...

    ------------=_1636817598-129950-3380
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 131533
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1032 AM EST Sat Nov 13 2021

    Day 1
    Valid 16Z Sat Nov 13 2021 - 12Z Sun Nov 14 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
    OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    16z Update:
    While the 12z RAOB sounding denoted average total PWat values
    (.58") at UIL this morning, CIRA Layered Precipitable Water (LPW)
    suite shows enhanced moisture supporting forecast values of
    1.3-1.6" along and east of the main cold front quickly advancing
    with the shortwave feature and developing surface cyclone (near
    45N138W). Observational trends along with 12z CAMs suggest some
    modest instability is present at/along the warm front and warm
    sector with values of 250 J/kg. As such, timing of the frontal
    zone and intersection with the Olympic peninsula should see light
    showers around 00z before the potential for stronger shallow
    updrafts around 03z-04z. HRRR and ARW solutions all support
    multiple hours (2-3) of .5"/hr rates along the western slopes,
    with occasional maximum rates up to .75"/hr resulting in pockets
    of 2-3" totals along the Olympic Range before translating to the
    central and northern Washington Cascades. This is a slight uptick
    in intensity; however, the short-duration with respect to typical
    AR suggests impact will be just below Slight Risk category. As
    such, no changes were made to the placement of the Marginal Risk
    for Day 1.

    Gallina

    ---Prior Discussion---
    With broad area of subtropical moisture and maturing Warm Conveyor
    Belt (WCB) in place across the northeast Pacific Ocean, an
    elongated, flat mid-level vort lobe emerging from the sub-tropics
    will amplify along the southeast periphery of the larger scale
    Gulf of Alaska closed low...leading to strengthening mid-upper
    level confluence and a tightened N-S upper height gradient. As
    this occurs, the bolstered WCB will funnel toward the Pacific
    Northwest, along with a sharpening warm front. Total PWs of
    1.25-1.5" will pool along the front with a 50-60kt southwesterly
    jet enhancing the strong WAA along and ahead of the boundary into
    the Olympic Peninsula toward 00-03Z Sunday. 850-700 mb moisture
    flux anomalies are between +3 and +4 standard deviations per the
    GEFS, while the aforementioned PWs would approach or exceed the
    daily record at UIL for mid November per the SPC sounding
    climatology page.

    The limiting factor is going to be duration of this event, not
    starting in earnest until the latter half of the period (after 00Z
    Sun), along with the warm front and associated robust deep-layer
    WAA/isentropic ascent peaking around 06Z before quickly waning
    toward 12Z. With that stated, 00Z high-res CAMs depict hourly
    rates in excess of .5"/hr and 1.5-3+" totals by 12Z. Given 0-100cm
    soil saturation values are nearly 100% per NASA SPoRT, this should
    result in nearly all rainfall running off increasing rapid onset
    flooding risk. While freezing levels will initially be at or just
    below the higher peaks level (mainly in the Cascades), the
    strength of the WAA, coupled with rainfall could also quickly
    convert any of the snow to runoff as well. As such, the Marginal
    Risk that was added to yesterday's Day 2 ERO will continue into
    the Day 1 period, mainly after 00Z Sunday, for the Olympic Range
    and Northern Cascade range of Washington.

    Hurley


    Day 2
    Valid 12Z Sun Nov 14 2021 - 12Z Mon Nov 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE OLYMPIC
    PENINSULA AND NORTHERN WASHINGTON CASCADES...

    After the initial moisture surge with the warm front early Sunday
    morning, there may be some residual enhanced convergence lingering
    through the northern Washington Cascades at the start of the Day 2
    forecast time period (12Z 11/14). Synoptically, the leading
    shortwave will remain focused making landfall into central BC by
    early morning Sunday, while the upstream larger-scale trough
    begins to phase with the southern stream wave around 42N/135W
    toward the end of the day 2 period (12Z 11/15). As such the
    subtropical moisture plume will once again narrow and focus north
    of the U.S. boarder into Vancouver Island. Southwesterly 850 mb
    onshore flow around 35-50 kts will keep modest ascent and moisture
    convergence for lighter showers across the Olympic Peninsula into
    the Northern Cascades with freezing levels rising above all but
    the most extreme peaks.=20

    There had been some uncertainty to the timing of the shortwave and
    therefore the placement and southward push of the frontal zone and
    pre-frontal Atmospheric River (AR) by early afternoon Sunday into
    Sunday night. Recent trends suggest increasing confidence toward
    the boundary sliding south into western Washington before stalling
    ahead of the further upstream larger scale height-falls. This will
    allow the elongated AR to remain directed into western WA and the
    northern WA Cascades for several hours, as the initial WSW-ENE
    orientation of the AR becomes more SW-NE oriented Sunday night. A
    prolonged period of deep-layer moisture transport and orographic
    enhancement along the frontal zone, accompanied by 1-1.25" Total
    PW Values support a longer duration moderate to heavy rainfall
    event Sun-Sun night.

    During the entire D2 period (12Z Sun 11/14-12Z Mon 11/15), the
    Center for Western Weather and Water Extremes (CW3E) is
    forecasting a level 4 AR with integrated water vapor transport or
    IVT persisting between 500-750 kg/m/s. The ECMWF, UKMET, and GEM global/regional runs indicate 24hr totals of 3-6+ inches across
    the Olympic Peninsula and northern WA Cascades; however, the GFS
    is slower with the frontal push and thus a bit farther north with
    the max QPF over the Cascades (highest totals across the border
    into southern BC). The FV3 is a bit farther south, supportive of
    the non-GFS camp, while the NAM CONUS Nest indicates scattered
    maxima over 7".

    As noted in the previous discussion, given the prolonged duration
    of this particular AR event, with nearly stationary or very slow
    southward progression of the boundary that is fairly orthogonal to
    the coastal ranges, a Slight Risk again appears warranted for the
    now Day 2 ERO period. Colorado State ERO first guess suggests
    20-35% probability of 1-2yr ARI exceedance, which appears to
    correlate well with a high-end Slight Risk.=20=20=20

    Hurley/Gallina


    Day 3
    Valid 12Z Mon Nov 15 2021 - 12Z Tue Nov 16 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
    THE OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    The aforementioned phased shortwaves and associated surface cold
    front will finally push onshore the Pacific NW coast by Monday
    afternoon. Behind the front, a precipitous drop in total PW and
    freezing levels will ensue, as the AR weakens and becomes more W-E
    oriented while dropping quickly southward into northern CA Monday
    night. Until then however (at least through early Monday
    afternoon), spotty 1hr rainfall rates ~0.50" with more widespread
    3hr rates of aoa 1.00" can still be expected across the Olympic
    Peninsula and northern-central WA Cascades. Maximum, additional
    areal-average QPF between 12-21Z Mon (prior to the frontal
    passage) is expected to range between 1.5 and 3+" per a non-GFS
    guidance consensus. The GFS meanwhile is much heavier compared to
    the rest of the guidance (more widespread areas of 3-5" over the
    Olympics and northern WA Cascades), due to the slower progression
    of the upper trough/surface front and pre-frontal AR compared to
    the other models. Will include a Marginal Risk in the Day 3 ERO
    (12Z Mon-12Z Tue) to bridge the Slight Risk on Day 2 to a much
    drier regime by Day 4 (Tue-Tue night).

    Hurley




    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!rcctJ4qqJZM2wOF1EloM_YI9BH1yTo85D3pkOSHl8I00= f3Wq9eqky_xDEkYCNHtOCttCo_U3$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!rcctJ4qqJZM2wOF1EloM_YI9BH1yTo85D3pkOSHl8I00= f3Wq9eqky_xDEkYCNHtOClnKjKs4$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!rcctJ4qqJZM2wOF1EloM_YI9BH1yTo85D3pkOSHl8I00= f3Wq9eqky_xDEkYCNHtOCsn30dpq$=20


    $$




    ------------=_1636817598-129950-3380
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636817598-129950-3380--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Nov 13 19:44:16 2021
    This is a multi-part message in MIME format...

    ------------=_1636832659-129950-3509
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 131944
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    243 PM EST Sat Nov 13 2021

    Day 1
    Valid 16Z Sat Nov 13 2021 - 12Z Sun Nov 14 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
    OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    16z Update:
    While the 12z RAOB sounding denoted average total PWat values
    (.58") at UIL this morning, CIRA Layered Precipitable Water (LPW)
    suite shows enhanced moisture supporting forecast values of
    1.3-1.6" along and east of the main cold front quickly advancing
    with the shortwave feature and developing surface cyclone (near
    45N138W). Observational trends along with 12z CAMs suggest some
    modest instability is present at/along the warm front and warm
    sector with values of 250 J/kg. As such, timing of the frontal
    zone and intersection with the Olympic peninsula should see light
    showers around 00z before the potential for stronger shallow
    updrafts around 03z-04z. HRRR and ARW solutions all support
    multiple hours (2-3) of .5"/hr rates along the western slopes,
    with occasional maximum rates up to .75"/hr resulting in pockets
    of 2-3" totals along the Olympic Range before translating to the
    central and northern Washington Cascades. This is a slight uptick
    in intensity; however, the short-duration with respect to typical
    AR suggests impact will be just below Slight Risk category. As
    such, no changes were made to the placement of the Marginal Risk
    for Day 1.

    Gallina

    ---Prior Discussion---
    With broad area of subtropical moisture and maturing Warm Conveyor
    Belt (WCB) in place across the northeast Pacific Ocean, an
    elongated, flat mid-level vort lobe emerging from the sub-tropics
    will amplify along the southeast periphery of the larger scale
    Gulf of Alaska closed low...leading to strengthening mid-upper
    level confluence and a tightened N-S upper height gradient. As
    this occurs, the bolstered WCB will funnel toward the Pacific
    Northwest, along with a sharpening warm front. Total PWs of
    1.25-1.5" will pool along the front with a 50-60kt southwesterly
    jet enhancing the strong WAA along and ahead of the boundary into
    the Olympic Peninsula toward 00-03Z Sunday. 850-700 mb moisture
    flux anomalies are between +3 and +4 standard deviations per the
    GEFS, while the aforementioned PWs would approach or exceed the
    daily record at UIL for mid November per the SPC sounding
    climatology page.

    The limiting factor is going to be duration of this event, not
    starting in earnest until the latter half of the period (after 00Z
    Sun), along with the warm front and associated robust deep-layer
    WAA/isentropic ascent peaking around 06Z before quickly waning
    toward 12Z. With that stated, 00Z high-res CAMs depict hourly
    rates in excess of .5"/hr and 1.5-3+" totals by 12Z. Given 0-100cm
    soil saturation values are nearly 100% per NASA SPoRT, this should
    result in nearly all rainfall running off increasing rapid onset
    flooding risk. While freezing levels will initially be at or just
    below the higher peaks level (mainly in the Cascades), the
    strength of the WAA, coupled with rainfall could also quickly
    convert any of the snow to runoff as well. As such, the Marginal
    Risk that was added to yesterday's Day 2 ERO will continue into
    the Day 1 period, mainly after 00Z Sunday, for the Olympic Range
    and Northern Cascade range of Washington.

    Hurley


    Day 2
    Valid 12Z Sun Nov 14 2021 - 12Z Mon Nov 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE OLYMPIC
    PENINSULA AND NORTHERN WASHINGTON CASCADES...

    21z Update:
    A notable but not significant shift toward a greater amplification
    of the initial shortwave late on Day 1 into early Day 2, denotes a
    bit stronger downstream ridging and less orthogonal orientation of
    the frontal zone and maximized moisture convergence zone across
    Washington into British Columbia. A slight thinning of the AR
    moisture plume Sunday afternoon into evening and directed flow
    focused greater into Vancouver Island and downstream into the
    Southern Canadian Cascade and Rockies has resulted in a overall
    reduction in rainfall totals across the region per global
    guidance.

    The main 5 global members (NAM, GFS, CMC, ECMWF,UKMET) supported
    by the their respective ensembles, generally reduced by about 1"
    over the 24hr period with totals of 3-5" focused on far NW Olympic
    peninsula to northern Washington Cascades, though with greatest
    totals now shifted north of the US/Canada boarder. Now that all
    12z Hi-Res CAMs forecast period stretches through the entire D2
    period, there are overall increased rainfall totals are forecast
    based on the higher resolutions, resulting in higher average
    totals. The GEM Regional and NAM_Conest depicted typical high
    biases with isolated 9-12+" totals seem much to aggressive but the
    HRRR and ARW solutions present a more reasonable 4-6+" totals
    within the ARWs and HRRR solutions. So this is an odd forecast
    period where WPC QPF remained about the same driven by higher fidelity/confidence in higher resolution guidance while the
    overall trend was reducing in the global and global ensemble
    guidance due to less favorable orientation and placement of the AR
    a bit further north. Still, all things considered especially the
    saturated grounds and prolonged duration of light to moderate rain
    rates, particularly increasing after 15.00z, a high-end Slight
    Risk potential is warranted especially exceeding longer-duration
    FFG values 6-24hr) further enhancing major to near record river
    flooding (per NWC/NWM and NWRFC).

    Gallina=20=20


    ---Prior Discussion---
    After the initial moisture surge with the warm front early Sunday
    morning, there may be some residual enhanced convergence lingering
    through the northern Washington Cascades at the start of the Day 2
    forecast time period (12Z 11/14). Synoptically, the leading
    shortwave will remain focused making landfall into central BC by
    early morning Sunday, while the upstream larger-scale trough
    begins to phase with the southern stream wave around 42N/135W
    toward the end of the day 2 period (12Z 11/15). As such the
    subtropical moisture plume will once again narrow and focus north
    of the U.S. boarder into Vancouver Island. Southwesterly 850 mb
    onshore flow around 35-50 kts will keep modest ascent and moisture
    convergence for lighter showers across the Olympic Peninsula into
    the Northern Cascades with freezing levels rising above all but
    the most extreme peaks.=20

    There had been some uncertainty to the timing of the shortwave and
    therefore the placement and southward push of the frontal zone and
    pre-frontal Atmospheric River (AR) by early afternoon Sunday into
    Sunday night. Recent trends suggest increasing confidence toward
    the boundary sliding south into western Washington before stalling
    ahead of the further upstream larger scale height-falls. This will
    allow the elongated AR to remain directed into western WA and the
    northern WA Cascades for several hours, as the initial WSW-ENE
    orientation of the AR becomes more SW-NE oriented Sunday night. A
    prolonged period of deep-layer moisture transport and orographic
    enhancement along the frontal zone, accompanied by 1-1.25" Total
    PW Values support a longer duration moderate to heavy rainfall
    event Sun-Sun night.

    During the entire D2 period (12Z Sun 11/14-12Z Mon 11/15), the
    Center for Western Weather and Water Extremes (CW3E) is
    forecasting a level 4 AR with integrated water vapor transport or
    IVT persisting between 500-750 kg/m/s. The ECMWF, UKMET, and GEM global/regional runs indicate 24hr totals of 3-6+ inches across
    the Olympic Peninsula and northern WA Cascades; however, the GFS
    is slower with the frontal push and thus a bit farther north with
    the max QPF over the Cascades (highest totals across the border
    into southern BC). The FV3 is a bit farther south, supportive of
    the non-GFS camp, while the NAM CONUS Nest indicates scattered
    maxima over 7".

    As noted in the previous discussion, given the prolonged duration
    of this particular AR event, with nearly stationary or very slow
    southward progression of the boundary that is fairly orthogonal to
    the coastal ranges, a Slight Risk again appears warranted for the
    now Day 2 ERO period. Colorado State ERO first guess suggests
    20-35% probability of 1-2yr ARI exceedance, which appears to
    correlate well with a high-end Slight Risk.=20=20=20

    Hurley


    Day 3

    The Day 3 outlook will be updated by 2030Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!r2KzF3a54QmD1RvzJFmA8tZ_2YGPZoikRp5a46q5Px2y= cIzuOcO72pW2rGtPtsNt23X8iSOm$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!r2KzF3a54QmD1RvzJFmA8tZ_2YGPZoikRp5a46q5Px2y= cIzuOcO72pW2rGtPtsNt26Oyx5li$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!r2KzF3a54QmD1RvzJFmA8tZ_2YGPZoikRp5a46q5Px2y= cIzuOcO72pW2rGtPtsNt2xPAO33A$=20


    $$




    ------------=_1636832659-129950-3509
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636832659-129950-3509--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Nov 13 19:45:16 2021
    This is a multi-part message in MIME format...

    ------------=_1636832719-129950-3510
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 131945
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    244 PM EST Sat Nov 13 2021

    Day 1
    Valid 16Z Sat Nov 13 2021 - 12Z Sun Nov 14 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
    OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    16z Update:
    While the 12z RAOB sounding denoted average total PWat values
    (.58") at UIL this morning, CIRA Layered Precipitable Water (LPW)
    suite shows enhanced moisture supporting forecast values of
    1.3-1.6" along and east of the main cold front quickly advancing
    with the shortwave feature and developing surface cyclone (near
    45N138W). Observational trends along with 12z CAMs suggest some
    modest instability is present at/along the warm front and warm
    sector with values of 250 J/kg. As such, timing of the frontal
    zone and intersection with the Olympic peninsula should see light
    showers around 00z before the potential for stronger shallow
    updrafts around 03z-04z. HRRR and ARW solutions all support
    multiple hours (2-3) of .5"/hr rates along the western slopes,
    with occasional maximum rates up to .75"/hr resulting in pockets
    of 2-3" totals along the Olympic Range before translating to the
    central and northern Washington Cascades. This is a slight uptick
    in intensity; however, the short-duration with respect to typical
    AR suggests impact will be just below Slight Risk category. As
    such, no changes were made to the placement of the Marginal Risk
    for Day 1.

    Gallina

    ---Prior Discussion---
    With broad area of subtropical moisture and maturing Warm Conveyor
    Belt (WCB) in place across the northeast Pacific Ocean, an
    elongated, flat mid-level vort lobe emerging from the sub-tropics
    will amplify along the southeast periphery of the larger scale
    Gulf of Alaska closed low...leading to strengthening mid-upper
    level confluence and a tightened N-S upper height gradient. As
    this occurs, the bolstered WCB will funnel toward the Pacific
    Northwest, along with a sharpening warm front. Total PWs of
    1.25-1.5" will pool along the front with a 50-60kt southwesterly
    jet enhancing the strong WAA along and ahead of the boundary into
    the Olympic Peninsula toward 00-03Z Sunday. 850-700 mb moisture
    flux anomalies are between +3 and +4 standard deviations per the
    GEFS, while the aforementioned PWs would approach or exceed the
    daily record at UIL for mid November per the SPC sounding
    climatology page.

    The limiting factor is going to be duration of this event, not
    starting in earnest until the latter half of the period (after 00Z
    Sun), along with the warm front and associated robust deep-layer
    WAA/isentropic ascent peaking around 06Z before quickly waning
    toward 12Z. With that stated, 00Z high-res CAMs depict hourly
    rates in excess of .5"/hr and 1.5-3+" totals by 12Z. Given 0-100cm
    soil saturation values are nearly 100% per NASA SPoRT, this should
    result in nearly all rainfall running off increasing rapid onset
    flooding risk. While freezing levels will initially be at or just
    below the higher peaks level (mainly in the Cascades), the
    strength of the WAA, coupled with rainfall could also quickly
    convert any of the snow to runoff as well. As such, the Marginal
    Risk that was added to yesterday's Day 2 ERO will continue into
    the Day 1 period, mainly after 00Z Sunday, for the Olympic Range
    and Northern Cascade range of Washington.

    Hurley


    Day 2
    Valid 12Z Sun Nov 14 2021 - 12Z Mon Nov 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE OLYMPIC
    PENINSULA AND NORTHERN WASHINGTON CASCADES...

    21z Update:
    A notable but not significant shift toward a greater amplification
    of the initial shortwave late on Day 1 into early Day 2, denotes a
    bit stronger downstream ridging and less orthogonal orientation of
    the frontal zone and maximized moisture convergence zone across
    Washington into British Columbia. A slight thinning of the AR
    moisture plume Sunday afternoon into evening and directed flow
    focused greater into Vancouver Island and downstream into the
    Southern Canadian Cascade and Rockies has resulted in a overall
    reduction in rainfall totals across the region per global
    guidance.

    The main 5 global members (NAM, GFS, CMC, ECMWF,UKMET) supported
    by the their respective ensembles, generally reduced by about 1"
    over the 24hr period with totals of 3-5" focused on far NW Olympic
    peninsula to northern Washington Cascades, though with greatest
    totals now shifted north of the US/Canada boarder. Now that all
    12z Hi-Res CAMs forecast period stretches through the entire D2
    period, there are overall increased rainfall totals are forecast
    based on the higher resolutions, resulting in higher average
    totals. The GEM Regional and NAM_Conest depicted typical high
    biases with isolated 9-12+" totals seem much to aggressive but the
    HRRR and ARW solutions present a more reasonable 4-6+" totals
    within the ARWs and HRRR solutions. So this is an odd forecast
    period where WPC QPF remained about the same driven by higher fidelity/confidence in higher resolution guidance while the
    overall trend was reducing in the global and global ensemble
    guidance due to less favorable orientation and placement of the AR
    a bit further north. Still, all things considered especially the
    saturated grounds and prolonged duration of light to moderate rain
    rates, particularly increasing after 15.00z, a high-end Slight
    Risk potential is warranted especially exceeding longer-duration
    FFG values 6-24hr) further enhancing major to near record river
    flooding (per NWC/NWM and NWRFC).

    Gallina=20=20


    ---Prior Discussion---
    After the initial moisture surge with the warm front early Sunday
    morning, there may be some residual enhanced convergence lingering
    through the northern Washington Cascades at the start of the Day 2
    forecast time period (12Z 11/14). Synoptically, the leading
    shortwave will remain focused making landfall into central BC by
    early morning Sunday, while the upstream larger-scale trough
    begins to phase with the southern stream wave around 42N/135W
    toward the end of the day 2 period (12Z 11/15). As such the
    subtropical moisture plume will once again narrow and focus north
    of the U.S. boarder into Vancouver Island. Southwesterly 850 mb
    onshore flow around 35-50 kts will keep modest ascent and moisture
    convergence for lighter showers across the Olympic Peninsula into
    the Northern Cascades with freezing levels rising above all but
    the most extreme peaks.=20

    There had been some uncertainty to the timing of the shortwave and
    therefore the placement and southward push of the frontal zone and
    pre-frontal Atmospheric River (AR) by early afternoon Sunday into
    Sunday night. Recent trends suggest increasing confidence toward
    the boundary sliding south into western Washington before stalling
    ahead of the further upstream larger scale height-falls. This will
    allow the elongated AR to remain directed into western WA and the
    northern WA Cascades for several hours, as the initial WSW-ENE
    orientation of the AR becomes more SW-NE oriented Sunday night. A
    prolonged period of deep-layer moisture transport and orographic
    enhancement along the frontal zone, accompanied by 1-1.25" Total
    PW Values support a longer duration moderate to heavy rainfall
    event Sun-Sun night.

    During the entire D2 period (12Z Sun 11/14-12Z Mon 11/15), the
    Center for Western Weather and Water Extremes (CW3E) is
    forecasting a level 4 AR with integrated water vapor transport or
    IVT persisting between 500-750 kg/m/s. The ECMWF, UKMET, and GEM global/regional runs indicate 24hr totals of 3-6+ inches across
    the Olympic Peninsula and northern WA Cascades; however, the GFS
    is slower with the frontal push and thus a bit farther north with
    the max QPF over the Cascades (highest totals across the border
    into southern BC). The FV3 is a bit farther south, supportive of
    the non-GFS camp, while the NAM CONUS Nest indicates scattered
    maxima over 7".

    As noted in the previous discussion, given the prolonged duration
    of this particular AR event, with nearly stationary or very slow
    southward progression of the boundary that is fairly orthogonal to
    the coastal ranges, a Slight Risk again appears warranted for the
    now Day 2 ERO period. Colorado State ERO first guess suggests
    20-35% probability of 1-2yr ARI exceedance, which appears to
    correlate well with a high-end Slight Risk.=20=20=20

    Hurley


    Day 3
    Valid 12Z Mon Nov 15 2021 - 12Z Tue Nov 16 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
    THE OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    At the start of the forecast period 15.12z, there is increasing
    convergence in global guidance that the AR will be ongoing in
    earnest across the Olympic Peninsula and into the northern
    Washington Cascades. 850-7H 50-60kts of southwesterly flow
    along/southeast of the frontal zone will transport 1-1.25" Total
    PWats reducing to .75-1" into the Cascades, resulting in 500-700
    kg/m/s IVT values and best potential for excessive rates.

    Upstream strong height-falls from the approaching closed low will
    strengthen and veer low level flow and quickly press the cold
    front southward along the Washington Coast into Oregon and
    California AFTER 16.00z. As such, duration of rainfall along with
    crashing freezing levels will reduce the threat for flooding
    particularly further south across Oregon/California which had
    remained dry through the bulk of the AR on days 1 and 2. As
    such, maintained the Marginal Risk of Excessive Rainfall to those
    locations mostly affected on day 1 and 2 that will see a
    additional 1-3", this includes expasion to the Willapa Hills in
    southwest Washington per coordination with Portland WFO.=20

    Gallina




    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!qu7wc-_3Vz0AbtcM9hu8_ox5_6onOA56lUwqBwDlBbjs= 2zsyAcstIhUgOyZtqvcryI1X1jYD$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!qu7wc-_3Vz0AbtcM9hu8_ox5_6onOA56lUwqBwDlBbjs= 2zsyAcstIhUgOyZtqvcryCA_MNPG$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!qu7wc-_3Vz0AbtcM9hu8_ox5_6onOA56lUwqBwDlBbjs= 2zsyAcstIhUgOyZtqvcryOXqedj4$=20


    $$




    ------------=_1636832719-129950-3510
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636832719-129950-3510--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Nov 14 15:45:51 2021
    This is a multi-part message in MIME format...

    ------------=_1636904756-129950-3955
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 141545
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1045 AM EST Sun Nov 14 2021

    Day 1
    Valid 12Z Sun Nov 14 2021 - 12Z Mon Nov 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE OLYMPIC
    PENINSULA AND NORTHERN WASHINGTON CASCADES...

    16z update:
    CIRA LPW suite denotes surge of moisture associated with surface
    wave near 41N/141W is increasing along the length of the AR plume.
    This AR plume appears to be centering very near the NW tip of the
    Olympic Peninsula with very little wavering expected throughout
    the remainder of the day. This will bring fairly consistent but
    slowly increasing TPW values with that surge reaching to about
    1.25", though as the wave nears later in the period could reach up
    to 1.5 as the enhanced moisture in the lagging 7-5H layer nears
    with the surface wave/shortwave near 12z. With increased
    winds/moisture, IVT values in the core of the plume will average
    about 600 kg/m/s before increasing to 700-800 by the end of the
    forecast period. Along with orographic ascent, should provide
    consistent .25"/hr along the peaks of the Olympics and northern WA
    Cascades (up to .4"/hr in Canadian slopes). Along the edges of the
    plume across SW Washington toward Mt. Rainier, lesser moisture and
    rates are expected but again will be very consistent.

    12z Hi-Res CAMs all generally agree to the timing of the surface
    wave and increase in rainfall rates starting about 03z in the late evening/overnight hours. The trend has been for the peak of rain
    rates to be a tad later, centering around 12z...transitioning into
    Day 2. Rainfall totals will still be greater than 4-6" across the
    core of the Olympic and northern WA Cascades, but with a slight
    northerly shift, though Hi-Res CAMs suggest localized totals in
    excess of 7+" by 12z are possible. As such, very small
    adjustments were made to the Slight Risk toward the north. Totals
    are reduced across SW Washington terrain into the Southern WA
    Cascades, but given saturated ground conditions the Marginal Risk
    area continue to be justified.=20=20=20=20=20

    Gallina

    ---Prior Discussion---
    After the initial moisture surge with the warm front early this
    morning, there may be a brief respite with the coverage of the
    more intense rainfall rates across the Olympics and northern
    Cascades. Any break however will be short-lived, as the
    Atmospheric River (AR) aligns across the Olympic Peninsula and the
    northern WA Cascades and persists for a while. Synoptically, after
    the leading shortwave makes landfall into central BC by early this
    morning, the larger-scale trough upstream will begin to phase with
    the southern stream wave around 42N/135W Sunday night. As such,
    the subtropical moisture plume will once again narrow and focus
    over the Olympic Peninsula northeastward across the northern WA
    Cascades Sunday afternoon-Sunday night. Snow levels will remain
    quite high -- generally 7500-9000+ feet MSL -- given the strength
    and depth of the WAA behind the warm front. Until the Gulf of AK
    shortwave pivots and phases with the southern stream wave (by
    Monday morning), the WSW-ENE oriented surface front will stall
    across far NW WA and bordering Vancouver Island. This will allow
    the elongated AR to remain directed into western WA and the
    northern WA Cascades for several hours, as the initial WSW-ENE
    orientation of the AR becomes more SW-NE oriented toward the end
    of the Day 1 period (by 12Z Mon 11/15). A prolonged period of
    deep-layer moisture transport and orographic enhancement along the
    frontal zone, accompanied by 1-1.25" Total PW Values support a
    longer duration moderate to heavy rainfall event -- especially Sun
    afternoon and overnight.=20

    During the entire D1 period (12Z Sun 11/14-12Z Mon 11/15), the
    Center for Western Weather and Water Extremes (CW3E) is
    forecasting a level 4 AR per the preferred ECMWF solution, with
    integrated water vapor transport or IVT persisting between 500-800
    kg/m/s. The global guidance cluster fairly well with the swaths of
    3-6+ inches across the Olympic Peninsula and northern WA Cascades.
    Meanwhile, the latest HREF mean shows isolated pockets of 7-9"
    totals, supported by the WRF ARW members along with the 00/06Z
    HRRRs and FV3. The NAM CONUS Nest continues to exhibit a wet bias
    (indicating localized 9-12" totals), while the GEM regional
    remains quite broad (high areal bias) with the 4-8" totals.

    As noted in the previous discussions, given the prolonged duration
    of this particular AR event, with nearly stationary or very slow
    southward progression of the boundary that is fairly orthogonal to
    the coastal ranges, a Slight Risk again appears warranted for the
    now Day 1 ERO period.=20

    Hurley



    Day 2
    Valid 12Z Mon Nov 15 2021 - 12Z Tue Nov 16 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
    THE OLYMPIC PENINSULA AND WASHINGTON CASCADES...

    At the start of the forecast period (12Z Mon), there is good model
    consensus that the AR will be ongoing in earnest across the
    Olympic Peninsula and into the northern Washington Cascades. 45-60
    kt of 850-700 mb southwesterly flow along/southeast of the frontal
    zone will continue to transport 1-1.25" Total PWs into these areas
    for the first several hours of the D2 period, maintaining robust
    850-700 mb moisture transport and IVT values between 500-700
    kg/m/s. As the phased upper trough and surface cold front push
    onshore the Pacific NW between 18-21Z Mon, a quick drop in PWs and
    freezing levels will ensue, lowering the rainfall rates and
    leading to a quick changeover to snow at the higher elevations.

    Therefore, the limited duration of the more intense rain rates
    early in the period prior to the FROPA and crashing freezing
    levels will reduce the threat for flooding, particularly further
    south across Oregon/California which up to this point have
    remained dry during this most recent AR event. This despite the
    presence of weak post-frontal instability (MUCAPEs <400 J/kg) with
    the backing winds/increasing CAA aloft Monday afternoon. As such,
    maintained the Marginal Risk of Excessive Rainfall across
    locations mostly affected by the AR through the current Day 1
    period -- areas that are expected to see an additional 1-3" of
    rainfall prior to any changeover to snow.

    Hurley



    Day 3
    Valid 12Z Tue Nov 16 2021 - 12Z Wed Nov 17 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Hurley


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!rU13SDTBG2OgFfjgWiIypziOAlPqSuWJH7JTpXOxjamA= JG6_ykUUHJro9jWBahI7C6ULbKj5$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!rU13SDTBG2OgFfjgWiIypziOAlPqSuWJH7JTpXOxjamA= JG6_ykUUHJro9jWBahI7C1aJpJOL$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!rU13SDTBG2OgFfjgWiIypziOAlPqSuWJH7JTpXOxjamA= JG6_ykUUHJro9jWBahI7Cx8MTpEc$=20


    $$




    ------------=_1636904756-129950-3955
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636904756-129950-3955--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Nov 14 19:31:52 2021
    This is a multi-part message in MIME format...

    ------------=_1636918316-129950-4050
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 141931
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    231 PM EST Sun Nov 14 2021

    Day 1
    Valid 16Z Sun Nov 14 2021 - 12Z Mon Nov 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE OLYMPIC
    PENINSULA AND NORTHERN WASHINGTON CASCADES...

    16z update:
    CIRA LPW suite denotes surge of moisture associated with surface
    wave near 41N/141W is increasing along the length of the AR plume.
    This AR plume appears to be centering very near the NW tip of the
    Olympic Peninsula with very little wavering expected throughout
    the remainder of the day. This will bring fairly consistent but
    slowly increasing TPW values with that surge reaching to about
    1.25", though as the wave nears later in the period could reach up
    to 1.5 as the enhanced moisture in the lagging 7-5H layer nears
    with the surface wave/shortwave near 12z. With increased
    winds/moisture, IVT values in the core of the plume will average
    about 600 kg/m/s before increasing to 700-800 by the end of the
    forecast period. Along with orographic ascent, should provide
    consistent .25"/hr along the peaks of the Olympics and northern WA
    Cascades (up to .4"/hr in Canadian slopes). Along the edges of the
    plume across SW Washington toward Mt. Rainier, lesser moisture and
    rates are expected but again will be very consistent.

    12z Hi-Res CAMs all generally agree to the timing of the surface
    wave and increase in rainfall rates starting about 03z in the late evening/overnight hours. The trend has been for the peak of rain
    rates to be a tad later, centering around 12z...transitioning into
    Day 2. Rainfall totals will still be greater than 4-6" across the
    core of the Olympic and northern WA Cascades, but with a slight
    northerly shift, though Hi-Res CAMs suggest localized totals in
    excess of 7+" by 12z are possible. As such, very small
    adjustments were made to the Slight Risk toward the north. Totals
    are reduced across SW Washington terrain into the Southern WA
    Cascades, but given saturated ground conditions the Marginal Risk
    area continue to be justified.=20=20=20=20=20

    Gallina

    ---Prior Discussion---
    After the initial moisture surge with the warm front early this
    morning, there may be a brief respite with the coverage of the
    more intense rainfall rates across the Olympics and northern
    Cascades. Any break however will be short-lived, as the
    Atmospheric River (AR) aligns across the Olympic Peninsula and the
    northern WA Cascades and persists for a while. Synoptically, after
    the leading shortwave makes landfall into central BC by early this
    morning, the larger-scale trough upstream will begin to phase with
    the southern stream wave around 42N/135W Sunday night. As such,
    the subtropical moisture plume will once again narrow and focus
    over the Olympic Peninsula northeastward across the northern WA
    Cascades Sunday afternoon-Sunday night. Snow levels will remain
    quite high -- generally 7500-9000+ feet MSL -- given the strength
    and depth of the WAA behind the warm front. Until the Gulf of AK
    shortwave pivots and phases with the southern stream wave (by
    Monday morning), the WSW-ENE oriented surface front will stall
    across far NW WA and bordering Vancouver Island. This will allow
    the elongated AR to remain directed into western WA and the
    northern WA Cascades for several hours, as the initial WSW-ENE
    orientation of the AR becomes more SW-NE oriented toward the end
    of the Day 1 period (by 12Z Mon 11/15). A prolonged period of
    deep-layer moisture transport and orographic enhancement along the
    frontal zone, accompanied by 1-1.25" Total PW Values support a
    longer duration moderate to heavy rainfall event -- especially Sun
    afternoon and overnight.=20

    During the entire D1 period (12Z Sun 11/14-12Z Mon 11/15), the
    Center for Western Weather and Water Extremes (CW3E) is
    forecasting a level 4 AR per the preferred ECMWF solution, with
    integrated water vapor transport or IVT persisting between 500-800
    kg/m/s. The global guidance cluster fairly well with the swaths of
    3-6+ inches across the Olympic Peninsula and northern WA Cascades.
    Meanwhile, the latest HREF mean shows isolated pockets of 7-9"
    totals, supported by the WRF ARW members along with the 00/06Z
    HRRRs and FV3. The NAM CONUS Nest continues to exhibit a wet bias
    (indicating localized 9-12" totals), while the GEM regional
    remains quite broad (high areal bias) with the 4-8" totals.

    As noted in the previous discussions, given the prolonged duration
    of this particular AR event, with nearly stationary or very slow
    southward progression of the boundary that is fairly orthogonal to
    the coastal ranges, a Slight Risk again appears warranted for the
    now Day 1 ERO period.=20

    Hurley



    Day 2
    Valid 12Z Mon Nov 15 2021 - 12Z Tue Nov 16 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
    THE OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    21z update:
    Global guidance along with 12z Hi-Res CAM solutions denoted a
    slight slowing in the timing of the approaching shortwave and
    height-falls. The associated surface wave will have transitioned
    ashore into S BC, but the apex of the approaching shortwave will
    result in the the cold front pivoting in the vicinity of the
    Olympic Range between 12-15z. This will result in a longer
    duration of the plume across the Olympic Range and downstream into
    the northern Washington and southern Canadian Cascades. Nearly
    all Hi-res CAMs forecast rates in range of .5" for a 3-6 hour
    period centered on 12-18z time frame, occasionally reaching
    .75"/hr. This results in a general 1-2" increase in rainfall
    totals for the Day 2 period and 2-4" values by the end of the
    event. By 18-21z, height-falls/CAA will press the front quickly
    south and eastward across the region and crash freezing levels
    effectively ending the AR event for the most affected areas. Now
    that the peak rain-rates have shifted to the Day 2 period with
    enhanced overall totals, felt it was prudent to increase Excessive
    Rainfall category to a Slight Risk, as all rain is already
    compounding on saturated grounds in the area. A Marginal Risk
    continues southward for portions of southwest Washington into the
    central Washington Cascades that had seen rainfall though at lower
    totals, so may be affected by the short-duration intense rainfall
    rates as the cold front presses through between 18-16.00z.

    Gallina

    ---Prior Discussion---
    At the start of the forecast period (12Z Mon), there is good model
    consensus that the AR will be ongoing in earnest across the
    Olympic Peninsula and into the northern Washington Cascades. 45-60
    kt of 850-700 mb southwesterly flow along/southeast of the frontal
    zone will continue to transport 1-1.25" Total PWs into these areas
    for the first several hours of the D2 period, maintaining robust
    850-700 mb moisture transport and IVT values between 500-700
    kg/m/s. As the phased upper trough and surface cold front push
    onshore the Pacific NW between 18-21Z Mon, a quick drop in PWs and
    freezing levels will ensue, lowering the rainfall rates and
    leading to a quick changeover to snow at the higher elevations.

    Therefore, the limited duration of the more intense rain rates
    early in the period prior to the FROPA and crashing freezing
    levels will reduce the threat for flooding, particularly further
    south across Oregon/California which up to this point have
    remained dry during this most recent AR event. This despite the
    presence of weak post-frontal instability (MUCAPEs <400 J/kg) with
    the backing winds/increasing CAA aloft Monday afternoon. As such,
    maintained the Marginal Risk of Excessive Rainfall across
    locations mostly affected by the AR through the current Day 1
    period -- areas that are expected to see an additional 1-3" of
    rainfall prior to any changeover to snow.

    Hurley



    Day 3

    The Day 3 outlook will be updated by 2030Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!t9payblrTka0RQWiKdTVt2IvrP-NY9JMKqemWyljWAoN= -7jdkp9bqIn5A9b-49bMV39mqLTO$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!t9payblrTka0RQWiKdTVt2IvrP-NY9JMKqemWyljWAoN= -7jdkp9bqIn5A9b-49bMV9dJR-yn$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!t9payblrTka0RQWiKdTVt2IvrP-NY9JMKqemWyljWAoN= -7jdkp9bqIn5A9b-49bMV8U86BD6$=20


    $$




    ------------=_1636918316-129950-4050
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636918316-129950-4050--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Nov 14 19:32:26 2021
    This is a multi-part message in MIME format...

    ------------=_1636918351-129950-4051
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 141932
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    231 PM EST Sun Nov 14 2021

    Day 1
    Valid 16Z Sun Nov 14 2021 - 12Z Mon Nov 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE OLYMPIC
    PENINSULA AND NORTHERN WASHINGTON CASCADES...

    16z update:
    CIRA LPW suite denotes surge of moisture associated with surface
    wave near 41N/141W is increasing along the length of the AR plume.
    This AR plume appears to be centering very near the NW tip of the
    Olympic Peninsula with very little wavering expected throughout
    the remainder of the day. This will bring fairly consistent but
    slowly increasing TPW values with that surge reaching to about
    1.25", though as the wave nears later in the period could reach up
    to 1.5 as the enhanced moisture in the lagging 7-5H layer nears
    with the surface wave/shortwave near 12z. With increased
    winds/moisture, IVT values in the core of the plume will average
    about 600 kg/m/s before increasing to 700-800 by the end of the
    forecast period. Along with orographic ascent, should provide
    consistent .25"/hr along the peaks of the Olympics and northern WA
    Cascades (up to .4"/hr in Canadian slopes). Along the edges of the
    plume across SW Washington toward Mt. Rainier, lesser moisture and
    rates are expected but again will be very consistent.

    12z Hi-Res CAMs all generally agree to the timing of the surface
    wave and increase in rainfall rates starting about 03z in the late evening/overnight hours. The trend has been for the peak of rain
    rates to be a tad later, centering around 12z...transitioning into
    Day 2. Rainfall totals will still be greater than 4-6" across the
    core of the Olympic and northern WA Cascades, but with a slight
    northerly shift, though Hi-Res CAMs suggest localized totals in
    excess of 7+" by 12z are possible. As such, very small
    adjustments were made to the Slight Risk toward the north. Totals
    are reduced across SW Washington terrain into the Southern WA
    Cascades, but given saturated ground conditions the Marginal Risk
    area continue to be justified.=20=20=20=20=20

    Gallina

    ---Prior Discussion---
    After the initial moisture surge with the warm front early this
    morning, there may be a brief respite with the coverage of the
    more intense rainfall rates across the Olympics and northern
    Cascades. Any break however will be short-lived, as the
    Atmospheric River (AR) aligns across the Olympic Peninsula and the
    northern WA Cascades and persists for a while. Synoptically, after
    the leading shortwave makes landfall into central BC by early this
    morning, the larger-scale trough upstream will begin to phase with
    the southern stream wave around 42N/135W Sunday night. As such,
    the subtropical moisture plume will once again narrow and focus
    over the Olympic Peninsula northeastward across the northern WA
    Cascades Sunday afternoon-Sunday night. Snow levels will remain
    quite high -- generally 7500-9000+ feet MSL -- given the strength
    and depth of the WAA behind the warm front. Until the Gulf of AK
    shortwave pivots and phases with the southern stream wave (by
    Monday morning), the WSW-ENE oriented surface front will stall
    across far NW WA and bordering Vancouver Island. This will allow
    the elongated AR to remain directed into western WA and the
    northern WA Cascades for several hours, as the initial WSW-ENE
    orientation of the AR becomes more SW-NE oriented toward the end
    of the Day 1 period (by 12Z Mon 11/15). A prolonged period of
    deep-layer moisture transport and orographic enhancement along the
    frontal zone, accompanied by 1-1.25" Total PW Values support a
    longer duration moderate to heavy rainfall event -- especially Sun
    afternoon and overnight.=20

    During the entire D1 period (12Z Sun 11/14-12Z Mon 11/15), the
    Center for Western Weather and Water Extremes (CW3E) is
    forecasting a level 4 AR per the preferred ECMWF solution, with
    integrated water vapor transport or IVT persisting between 500-800
    kg/m/s. The global guidance cluster fairly well with the swaths of
    3-6+ inches across the Olympic Peninsula and northern WA Cascades.
    Meanwhile, the latest HREF mean shows isolated pockets of 7-9"
    totals, supported by the WRF ARW members along with the 00/06Z
    HRRRs and FV3. The NAM CONUS Nest continues to exhibit a wet bias
    (indicating localized 9-12" totals), while the GEM regional
    remains quite broad (high areal bias) with the 4-8" totals.

    As noted in the previous discussions, given the prolonged duration
    of this particular AR event, with nearly stationary or very slow
    southward progression of the boundary that is fairly orthogonal to
    the coastal ranges, a Slight Risk again appears warranted for the
    now Day 1 ERO period.=20

    Hurley



    Day 2
    Valid 12Z Mon Nov 15 2021 - 12Z Tue Nov 16 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
    THE OLYMPIC PENINSULA AND NORTHERN WASHINGTON CASCADES...

    21z update:
    Global guidance along with 12z Hi-Res CAM solutions denoted a
    slight slowing in the timing of the approaching shortwave and
    height-falls. The associated surface wave will have transitioned
    ashore into S BC, but the apex of the approaching shortwave will
    result in the the cold front pivoting in the vicinity of the
    Olympic Range between 12-15z. This will result in a longer
    duration of the plume across the Olympic Range and downstream into
    the northern Washington and southern Canadian Cascades. Nearly
    all Hi-res CAMs forecast rates in range of .5" for a 3-6 hour
    period centered on 12-18z time frame, occasionally reaching
    .75"/hr. This results in a general 1-2" increase in rainfall
    totals for the Day 2 period and 2-4" values by the end of the
    event. By 18-21z, height-falls/CAA will press the front quickly
    south and eastward across the region and crash freezing levels
    effectively ending the AR event for the most affected areas. Now
    that the peak rain-rates have shifted to the Day 2 period with
    enhanced overall totals, felt it was prudent to increase Excessive
    Rainfall category to a Slight Risk, as all rain is already
    compounding on saturated grounds in the area. A Marginal Risk
    continues southward for portions of southwest Washington into the
    central Washington Cascades that had seen rainfall though at lower
    totals, so may be affected by the short-duration intense rainfall
    rates as the cold front presses through between 18-16.00z.

    Gallina

    ---Prior Discussion---
    At the start of the forecast period (12Z Mon), there is good model
    consensus that the AR will be ongoing in earnest across the
    Olympic Peninsula and into the northern Washington Cascades. 45-60
    kt of 850-700 mb southwesterly flow along/southeast of the frontal
    zone will continue to transport 1-1.25" Total PWs into these areas
    for the first several hours of the D2 period, maintaining robust
    850-700 mb moisture transport and IVT values between 500-700
    kg/m/s. As the phased upper trough and surface cold front push
    onshore the Pacific NW between 18-21Z Mon, a quick drop in PWs and
    freezing levels will ensue, lowering the rainfall rates and
    leading to a quick changeover to snow at the higher elevations.

    Therefore, the limited duration of the more intense rain rates
    early in the period prior to the FROPA and crashing freezing
    levels will reduce the threat for flooding, particularly further
    south across Oregon/California which up to this point have
    remained dry during this most recent AR event. This despite the
    presence of weak post-frontal instability (MUCAPEs <400 J/kg) with
    the backing winds/increasing CAA aloft Monday afternoon. As such,
    maintained the Marginal Risk of Excessive Rainfall across
    locations mostly affected by the AR through the current Day 1
    period -- areas that are expected to see an additional 1-3" of
    rainfall prior to any changeover to snow.

    Hurley



    Day 3
    Valid 12Z Tue Nov 16 2021 - 12Z Wed Nov 17 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Gallina


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!tqnLYBGuDDFpM9X04y5gbzEfn0gwG08M5myDOjkH9xtU= f-aEaNMI632gVoKtkG5PAgyXsq45$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!tqnLYBGuDDFpM9X04y5gbzEfn0gwG08M5myDOjkH9xtU= f-aEaNMI632gVoKtkG5PAmDD-a2d$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!tqnLYBGuDDFpM9X04y5gbzEfn0gwG08M5myDOjkH9xtU= f-aEaNMI632gVoKtkG5PArIcVmLw$=20


    $$




    ------------=_1636918351-129950-4051
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1636918351-129950-4051--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Dec 11 15:46:37 2021
    This is a multi-part message in MIME format...

    ------------=_1639237600-34671-1989
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 111546
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1045 AM EST Sat Dec 11 2021

    Day 1
    Valid 12Z Sat Dec 11 2021 - 12Z Sun Dec 12 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
    WESTERN OREGON AND NORTHWEST CALIFORNIA, AND FROM PARTS OF
    SOUTHWEST WEST VIRGINIA/E KENTUCKY/E TENNESSEE INTO N
    GEORGIA/ALABAMA...

    16z update:
    No changes were required given new 12z guidance, and appears to be
    on track with initial forecast for the Oregon and northern
    California coastal ranges.

    Further east, the southwest to northeast oriented line of showers
    and thunderstorms continues to march eastward with a general
    downward trend in rainfall intensity. This is particularly the
    case along the southwest flank in LA/MS as a subtle speed max
    lifts northeast and away from the region. Higher FFG values are
    less likely to be exceeded, so have trimmed the Marginal to
    northern Alabama/northern Georgia where there are still a few
    stronger cells and 12z hi-res CAMS suggestive of isolated hourly
    totals of 1-1.25" for at least a few more hours. To the north
    across the Cumberland Plateau and into SW WV, the cells are
    generally weaker but supportive of .75-1" hourly totals as the
    lead convective line marches through. Lower FFG values in the
    more complex terrain as well as some mid-level lingering
    post-frontal showers still have a low end threat for isolated
    flash flooding conditions through about 21z as it clears the
    western slopes of the Appalachians.=20=20=20=20

    Gallina

    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~~
    ...Western Oregon and Northwest California...
    Atmospheric River event will progress southward along the
    Oregon/northern California coast today in advance of a cold front
    with precipitable water values around +1 to +1.5 sigma. Right
    entrance region of a 130-150kt upper jet will provide large-scale
    ascent that will be only somewhat enhanced on upslope flow into
    SSW-facing slopes (i.e., not maximized into the terrain). Rainfall
    over the 24-hr period will average 2-4" along the Coastal Ranges
    and coastline, with higher amounts (3-6+ inches) over southwestern
    Oregon. AR will be progressive enough through the day 1 period,
    and with the burn scars in the higher terrain where snow will be
    the dominant precipitation type, per collaboration with WFOs MFR
    and EKA have not upgraded any portion of the Marginal Risk area to
    a Slight.

    ...Eastern Kentucky and Tennessee southwestward into south-central
    Louisiana...
    Frontal boundary and pre-frontal QLCS will make steady progression eastward/southeastward today. Guidance indicates the best window
    of heavier rainfall and rates in the 12Z-00Z window amid gradually
    weakening support in moisture, lift, and instability. Recent 7-day
    rainfall anomalies are generally negative in the area of the
    Marginal Risk (and about 75% of normal) but near and above normal
    over portions of Louisiana. There, tail-end convection may fire
    and/or re-fire before the front clears the coast and stability
    increases. If these storms can materialize, sufficient
    moisture/instability and favorably-oriented flow aloft could
    result in a few areas of training and excessive rainfall. This
    risk is fairly conditional and will depend on upstream convective
    evolution. Risk areas will likely need to be adjusted in later
    outlooks.

    Hurley/Fracasso



    Day 2
    Valid 12Z Sun Dec 12 2021 - 12Z Mon Dec 13 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL AND NORTHERN CALIFORNIA, INCLUDING THE BAY
    AREA...

    ...West Coast...
    Strong upper jet streak and vigorous shortwave energy diving
    southeastward from the Gulf of Alaska will further amplify the
    deep low across the northern Pacific, as the longwave trough
    pivots closer to the central-northern West Coast toward the end of
    the day 2 forecast period (Sunday night). The amplification of the
    upstream trough/downstream ridge will cause the low-mid level flow
    to back s-sw once again, allowing the AR pressing southward during
    day 2 to re-emerge somewhere along the central CA coast into the
    central valleys with precipitable water values around 0.75-1.00"
    (+1 to +1.5 sigma).

    Models are in better agreement with respect to the orientation,
    location, and timing of the Atmospheric River (AR), thus there is
    fairly good consensus with the axis of heaviest QPF. Based on the
    increased forecast confidence, we have upgraded a portion of
    yesterday's Day 3 Marginal Risk to a Slight Risk from the southern
    coastal ranges south through the Bay area.
    This is where some of the available high-res CAMs, including the
    NAM CONUS Nest and FV3, show isolated totals of 3-5".
    Probabilities of >50"/hr rainfall rates will be highest within
    this area, which encompasses several burn scars from 2020
    (including the Hennessey scar).

    The latest output from the Center for Western Weather and Water
    Extremes (CW3E) shows a low-end 'moderate' or level 3 AR based on
    a 5 point scale on Day 2 (12Z Sun 12/12 to 12Z Mon 12/13), with
    the maximum integrated water vapor transport or IVT magnitude
    forecast just over 500 kg/m/s. Based on the strength of the
    dynamical forcing off the coast and potential robust
    thermodynamical response, would not be surprised to see an uptick
    in the projected AR strength as the event draws near. Multi-day
    ensemble trend has been mostly steadily increasing but still
    wavering in location owing to upstream timing/evolution
    differences (max QPF spread near/north of SFO).

    Fracasso/Hurley

    Day 3
    Valid 12Z Mon Dec 13 2021 - 12Z Tue Dec 14 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL CALIFORNIA, INCLUDING THE BAY AREA AND CENTRAL
    CALIFORNIA COAST...

    ...California...
    Amplifying mid-upper trough and associated surface front will
    approach the central CA coast on day 3 (Mon-Mon night). Max TPW
    values remain between 0.75-1.00" (not overly anomalous for mid
    December), however low-level moisture transport remains quite
    robust as 850 mb southwesterly flow peaks ~50 kts and 850-700 mb
    moisture flux anomalies average 3 to 4 standard deviations above
    normal. Guidance shows AR orientation backing slightly (SW to NE)
    on day 3 in response to the strong offshore height falls between
    31-35N. The guidance shows fairly good consensus with the heavy
    rainfall axis dropping a little farther south from day 2, across
    the Central CA Coast and into the Santa Lucia and Diablo Ranges.
    ECMWF, NAM, GFS, GEM, and UKMet all show at least a maximum of 4"
    within the Slight Risk area along the Central CA coast into the
    Santa Lucia Mountains, with >5" amounts per the NAM, ECMWF and GEM
    regional models. A period with rainfall rates exceeding 0.50" will
    be likely, especially within the Slight Risk area, which will
    enhance the flash flood and debris flow potential. Of particular
    concern will be over burn scar areas, including the Willow (2021)
    and River (2020) scars.

    Hurley


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!un9QUeTS_U3uwLjTDij2H8Tpghixh59piym3dcHBM6BQ= Pb9kjyxRbmXopdS6DIdF7IV6bTFU$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!un9QUeTS_U3uwLjTDij2H8Tpghixh59piym3dcHBM6BQ= Pb9kjyxRbmXopdS6DIdF7CpnHQ2A$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!un9QUeTS_U3uwLjTDij2H8Tpghixh59piym3dcHBM6BQ= Pb9kjyxRbmXopdS6DIdF7OagEqW3$=20


    $$




    ------------=_1639237600-34671-1989
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639237600-34671-1989--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Dec 11 19:46:39 2021
    This is a multi-part message in MIME format...

    ------------=_1639252004-34671-2491
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 111946
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    245 PM EST Sat Dec 11 2021

    Day 1
    Valid 16Z Sat Dec 11 2021 - 12Z Sun Dec 12 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
    WESTERN OREGON AND NORTHWEST CALIFORNIA, AND FROM PARTS OF
    SOUTHWEST WEST VIRGINIA/E KENTUCKY/E TENNESSEE INTO N
    GEORGIA/ALABAMA...

    16z update:
    No changes were required given new 12z guidance, and appears to be
    on track with initial forecast for the Oregon and northern
    California coastal ranges.

    Further east, the southwest to northeast oriented line of showers
    and thunderstorms continues to march eastward with a general
    downward trend in rainfall intensity. This is particularly the
    case along the southwest flank in LA/MS as a subtle speed max
    lifts northeast and away from the region. Higher FFG values are
    less likely to be exceeded, so have trimmed the Marginal to
    northern Alabama/northern Georgia where there are still a few
    stronger cells and 12z hi-res CAMS suggestive of isolated hourly
    totals of 1-1.25" for at least a few more hours. To the north
    across the Cumberland Plateau and into SW WV, the cells are
    generally weaker but supportive of .75-1" hourly totals as the
    lead convective line marches through. Lower FFG values in the
    more complex terrain as well as some mid-level lingering
    post-frontal showers still have a low end threat for isolated
    flash flooding conditions through about 21z as it clears the
    western slopes of the Appalachians.=20=20=20=20


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~~
    ...Western Oregon and Northwest California...
    Atmospheric River event will progress southward along the
    Oregon/northern California coast today in advance of a cold front
    with precipitable water values around +1 to +1.5 sigma. Right
    entrance region of a 130-150kt upper jet will provide large-scale
    ascent that will be only somewhat enhanced on upslope flow into
    SSW-facing slopes (i.e., not maximized into the terrain). Rainfall
    over the 24-hr period will average 2-4" along the Coastal Ranges
    and coastline, with higher amounts (3-6+ inches) over southwestern
    Oregon. AR will be progressive enough through the day 1 period,
    and with the burn scars in the higher terrain where snow will be
    the dominant precipitation type, per collaboration with WFOs MFR
    and EKA have not upgraded any portion of the Marginal Risk area to
    a Slight.

    ...Eastern Kentucky and Tennessee southwestward into south-central
    Louisiana...
    Frontal boundary and pre-frontal QLCS will make steady progression eastward/southeastward today. Guidance indicates the best window
    of heavier rainfall and rates in the 12Z-00Z window amid gradually
    weakening support in moisture, lift, and instability. Recent 7-day
    rainfall anomalies are generally negative in the area of the
    Marginal Risk (and about 75% of normal) but near and above normal
    over portions of Louisiana. There, tail-end convection may fire
    and/or re-fire before the front clears the coast and stability
    increases. If these storms can materialize, sufficient
    moisture/instability and favorably-oriented flow aloft could
    result in a few areas of training and excessive rainfall. This
    risk is fairly conditional and will depend on upstream convective
    evolution. Risk areas will likely need to be adjusted in later
    outlooks.

    Hurley/Fracasso



    Day 2
    Valid 12Z Sun Dec 12 2021 - 12Z Mon Dec 13 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL AND NORTHERN CALIFORNIA, INCLUDING SAN
    FRANCISCO AND MONTERREY BAY AREAS...

    21z update:
    ...West Coast...
    An overall trend for slightly faster southward push of the leading
    moisture plume late on Sunday into early Monday, results in the
    stalling of the plume a tad south toward Santa Cruz/Monterrey Bay.
    This results in increased moisture flux to the northern extension
    of the Santa Lucia and Sierra de Salinas ranges for the Day 2
    period. As a result, the Slight Risk has been expanded southward
    to account for this.

    The secondary approaching wave late on Monday lifting toward the
    central Oregon coast, will bring a secondary moisture surge
    further north toward southwest Oregon and northern California.=20
    However, freezing levels will have dropped significantly resulting
    in snowfall across the higher coastal terrain, leading to highest
    potential for excessive rainfall to precisely to coastal
    locations. Some Hi-Res CAMs solutions depict some weak
    instability due to the steeper lapse rates aloft and suggest some
    convective elements particularly near Cape Mendocino. Given
    today's rainfall, the Marginal Risk area will be included tightly
    to the coast.

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~
    Strong upper jet streak and vigorous shortwave energy diving
    southeastward from the Gulf of Alaska will further amplify the
    deep low across the northern Pacific, as the longwave trough
    pivots closer to the central-northern West Coast toward the end of
    the day 2 forecast period (Sunday night). The amplification of the
    upstream trough/downstream ridge will cause the low-mid level flow
    to back s-sw once again, allowing the AR pressing southward during
    day 2 to re-emerge somewhere along the central CA coast into the
    central valleys with precipitable water values around 0.75-1.00"
    (+1 to +1.5 sigma).

    Models are in better agreement with respect to the orientation,
    location, and timing of the Atmospheric River (AR), thus there is
    fairly good consensus with the axis of heaviest QPF. Based on the
    increased forecast confidence, we have upgraded a portion of
    yesterday's Day 3 Marginal Risk to a Slight Risk from the southern
    coastal ranges south through the Bay area.
    This is where some of the available high-res CAMs, including the
    NAM CONUS Nest and FV3, show isolated totals of 3-5".
    Probabilities of >50"/hr rainfall rates will be highest within
    this area, which encompasses several burn scars from 2020
    (including the Hennessey scar).

    The latest output from the Center for Western Weather and Water
    Extremes (CW3E) shows a low-end 'moderate' or level 3 AR based on
    a 5 point scale on Day 2 (12Z Sun 12/12 to 12Z Mon 12/13), with
    the maximum integrated water vapor transport or IVT magnitude
    forecast just over 500 kg/m/s. Based on the strength of the
    dynamical forcing off the coast and potential robust
    thermodynamical response, would not be surprised to see an uptick
    in the projected AR strength as the event draws near. Multi-day
    ensemble trend has been mostly steadily increasing but still
    wavering in location owing to upstream timing/evolution
    differences (max QPF spread near/north of SFO).

    Fracasso/Hurley

    Day 3

    The Day 3 outlook will be updated by 2030Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!t_oe-vn7j_HEW8_toHD8_IJGWBmKcBfsZfeRzER4YB06= gsLlKzCh_zoY8GslQmHVWwkVv9HI$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!t_oe-vn7j_HEW8_toHD8_IJGWBmKcBfsZfeRzER4YB06= gsLlKzCh_zoY8GslQmHVW7q0EGqa$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!t_oe-vn7j_HEW8_toHD8_IJGWBmKcBfsZfeRzER4YB06= gsLlKzCh_zoY8GslQmHVWzYhYPfh$=20


    $$




    ------------=_1639252004-34671-2491
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639252004-34671-2491--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Dec 11 19:47:39 2021
    This is a multi-part message in MIME format...

    ------------=_1639252064-34671-2492
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 111947
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    246 PM EST Sat Dec 11 2021

    Day 1
    Valid 16Z Sat Dec 11 2021 - 12Z Sun Dec 12 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
    WESTERN OREGON AND NORTHWEST CALIFORNIA, AND FROM PARTS OF
    SOUTHWEST WEST VIRGINIA/E KENTUCKY/E TENNESSEE INTO N
    GEORGIA/ALABAMA...

    16z update:
    No changes were required given new 12z guidance, and appears to be
    on track with initial forecast for the Oregon and northern
    California coastal ranges.

    Further east, the southwest to northeast oriented line of showers
    and thunderstorms continues to march eastward with a general
    downward trend in rainfall intensity. This is particularly the
    case along the southwest flank in LA/MS as a subtle speed max
    lifts northeast and away from the region. Higher FFG values are
    less likely to be exceeded, so have trimmed the Marginal to
    northern Alabama/northern Georgia where there are still a few
    stronger cells and 12z hi-res CAMS suggestive of isolated hourly
    totals of 1-1.25" for at least a few more hours. To the north
    across the Cumberland Plateau and into SW WV, the cells are
    generally weaker but supportive of .75-1" hourly totals as the
    lead convective line marches through. Lower FFG values in the
    more complex terrain as well as some mid-level lingering
    post-frontal showers still have a low end threat for isolated
    flash flooding conditions through about 21z as it clears the
    western slopes of the Appalachians.=20=20=20=20


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~~
    ...Western Oregon and Northwest California...
    Atmospheric River event will progress southward along the
    Oregon/northern California coast today in advance of a cold front
    with precipitable water values around +1 to +1.5 sigma. Right
    entrance region of a 130-150kt upper jet will provide large-scale
    ascent that will be only somewhat enhanced on upslope flow into
    SSW-facing slopes (i.e., not maximized into the terrain). Rainfall
    over the 24-hr period will average 2-4" along the Coastal Ranges
    and coastline, with higher amounts (3-6+ inches) over southwestern
    Oregon. AR will be progressive enough through the day 1 period,
    and with the burn scars in the higher terrain where snow will be
    the dominant precipitation type, per collaboration with WFOs MFR
    and EKA have not upgraded any portion of the Marginal Risk area to
    a Slight.

    ...Eastern Kentucky and Tennessee southwestward into south-central
    Louisiana...
    Frontal boundary and pre-frontal QLCS will make steady progression eastward/southeastward today. Guidance indicates the best window
    of heavier rainfall and rates in the 12Z-00Z window amid gradually
    weakening support in moisture, lift, and instability. Recent 7-day
    rainfall anomalies are generally negative in the area of the
    Marginal Risk (and about 75% of normal) but near and above normal
    over portions of Louisiana. There, tail-end convection may fire
    and/or re-fire before the front clears the coast and stability
    increases. If these storms can materialize, sufficient
    moisture/instability and favorably-oriented flow aloft could
    result in a few areas of training and excessive rainfall. This
    risk is fairly conditional and will depend on upstream convective
    evolution. Risk areas will likely need to be adjusted in later
    outlooks.

    Hurley/Fracasso



    Day 2
    Valid 12Z Sun Dec 12 2021 - 12Z Mon Dec 13 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL AND NORTHERN CALIFORNIA, INCLUDING SAN
    FRANCISCO AND MONTERREY BAY AREAS...

    21z update:
    ...West Coast...
    An overall trend for slightly faster southward push of the leading
    moisture plume late on Sunday into early Monday, results in the
    stalling of the plume a tad south toward Santa Cruz/Monterrey Bay.
    This results in increased moisture flux to the northern extension
    of the Santa Lucia and Sierra de Salinas ranges for the Day 2
    period. As a result, the Slight Risk has been expanded southward
    to account for this.

    The secondary approaching wave late on Monday lifting toward the
    central Oregon coast, will bring a secondary moisture surge
    further north toward southwest Oregon and northern California.=20
    However, freezing levels will have dropped significantly resulting
    in snowfall across the higher coastal terrain, leading to highest
    potential for excessive rainfall to precisely to coastal
    locations. Some Hi-Res CAMs solutions depict some weak
    instability due to the steeper lapse rates aloft and suggest some
    convective elements particularly near Cape Mendocino. Given
    today's rainfall, the Marginal Risk area will be included tightly
    to the coast.

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~
    Strong upper jet streak and vigorous shortwave energy diving
    southeastward from the Gulf of Alaska will further amplify the
    deep low across the northern Pacific, as the longwave trough
    pivots closer to the central-northern West Coast toward the end of
    the day 2 forecast period (Sunday night). The amplification of the
    upstream trough/downstream ridge will cause the low-mid level flow
    to back s-sw once again, allowing the AR pressing southward during
    day 2 to re-emerge somewhere along the central CA coast into the
    central valleys with precipitable water values around 0.75-1.00"
    (+1 to +1.5 sigma).

    Models are in better agreement with respect to the orientation,
    location, and timing of the Atmospheric River (AR), thus there is
    fairly good consensus with the axis of heaviest QPF. Based on the
    increased forecast confidence, we have upgraded a portion of
    yesterday's Day 3 Marginal Risk to a Slight Risk from the southern
    coastal ranges south through the Bay area.
    This is where some of the available high-res CAMs, including the
    NAM CONUS Nest and FV3, show isolated totals of 3-5".
    Probabilities of >50"/hr rainfall rates will be highest within
    this area, which encompasses several burn scars from 2020
    (including the Hennessey scar).

    The latest output from the Center for Western Weather and Water
    Extremes (CW3E) shows a low-end 'moderate' or level 3 AR based on
    a 5 point scale on Day 2 (12Z Sun 12/12 to 12Z Mon 12/13), with
    the maximum integrated water vapor transport or IVT magnitude
    forecast just over 500 kg/m/s. Based on the strength of the
    dynamical forcing off the coast and potential robust
    thermodynamical response, would not be surprised to see an uptick
    in the projected AR strength as the event draws near. Multi-day
    ensemble trend has been mostly steadily increasing but still
    wavering in location owing to upstream timing/evolution
    differences (max QPF spread near/north of SFO).

    Fracasso/Hurley

    Day 3
    Valid 12Z Mon Dec 13 2021 - 12Z Tue Dec 14 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL AND SOUTHERN CALIFORNIA...

    21z update:
    ...California...
    At the start of the period, 13.12z, the lead moisture plume should
    be nearing peak backing of the low level flow and generally
    centered near the Santa Cruz Range which as noted in the Day 2
    discussion, has trended a bit south. Likewise, the approaching
    secondary wave/moisture surge (limited to ~.75" TPW) is a bit
    faster/south and is expected to press the initial cold
    front/moisture plume southward accelerating flow to over 50kts at
    850mb while increasing flux anomalies to 3 to 4 standard
    deviations about 13.21z to the end of the forecast period.=20
    Southward progression may reduce duration at any given point south
    of the Santa Lucia range, but rates will increase to over .75"
    perhaps to 1" in the steepest/south-southwest facing orography.=20
    This seems to be case as the plume rounds Point Conception
    overnight Tuesday. Overall trends see an increase of QPF across
    the Western Transverse Ranges of Santa Barbara and Ventura
    counties before 14.12z. Given this and in coordination with WFO
    Oxnard, we have added a Slight Risk to the this area.

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~~~
    Amplifying mid-upper trough and associated surface front will
    approach the central CA coast on day 3 (Mon-Mon night). Max TPW
    values remain between 0.75-1.00" (not overly anomalous for mid
    December), however low-level moisture transport remains quite
    robust as 850 mb southwesterly flow peaks ~50 kts and 850-700 mb
    moisture flux anomalies average 3 to 4 standard deviations above
    normal. Guidance shows AR orientation backing slightly (SW to NE)
    on day 3 in response to the strong offshore height falls between
    31-35N. The guidance shows fairly good consensus with the heavy
    rainfall axis dropping a little farther south from day 2, across
    the Central CA Coast and into the Santa Lucia and Diablo Ranges.
    ECMWF, NAM, GFS, GEM, and UKMet all show at least a maximum of 4"
    within the Slight Risk area along the Central CA coast into the
    Santa Lucia Mountains, with >5" amounts per the NAM, ECMWF and GEM
    regional models. A period with rainfall rates exceeding 0.50" will
    be likely, especially within the Slight Risk area, which will
    enhance the flash flood and debris flow potential. Of particular
    concern will be over burn scar areas, including the Willow (2021)
    and River (2020) scars.

    Hurley


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!uUomjwxRCB_xrWtd0Cvj1oSG0e-RbdvZS_MOHQHMxUtm= LsBFbg1HQKwe69CjYUWiUlprH4Q1$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!uUomjwxRCB_xrWtd0Cvj1oSG0e-RbdvZS_MOHQHMxUtm= LsBFbg1HQKwe69CjYUWiUulMY053$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!uUomjwxRCB_xrWtd0Cvj1oSG0e-RbdvZS_MOHQHMxUtm= LsBFbg1HQKwe69CjYUWiUiFRWhhW$=20


    $$




    ------------=_1639252064-34671-2492
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639252064-34671-2492--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Dec 12 15:37:22 2021
    This is a multi-part message in MIME format...

    ------------=_1639323446-34671-3306
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 121537
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1034 AM EST Sun Dec 12 2021

    Day 1
    Valid 12Z Sun Dec 12 2021 - 12Z Mon Dec 13 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL AND NORTHERN CALIFORNIA, INCLUDING SAN
    FRANCISCO AND MONTERREY BAY AREAS...

    16z update:
    ...California...
    Leading primary axis of moisture core is currently centered
    along/south of the mouth of San Francisco Bay, so have made some
    small adjustments to the northern edges of Slight Risk area for
    North Bay counties and was considering removing the Marginal Risk
    for the dry slot gap ahead of the secondary moisture surge
    associated with next shortwave/height-falls approaching by the end
    of the forecast period. However, the 12z Hi-Res CAMs show some
    timing differences that may keep central and southern Mendocino
    and Sonoma counties in play for some scattered showers/increased
    moisture flux by 13.12z to not get too precise in drawing this
    gap; even though it is more likely to be post-13.12z into the day
    2 period. Otherwise further south, the timing/placement appears
    to be on target from prior thinking with only a slight trend for
    increased rainfall rates (.5-.75"/hr) with 90%+ HREF probability
    of 24hr totals of 3" (~30% for 5"+) for the Santa Cruz Mountains;
    however, the increase is not substantial in comparison to prior
    cycles to warrant an increase in category.=20=20

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    Strong upper jet streak and vigorous shortwave energy diving
    southeastward from the Gulf of Alaska will further amplify the
    deep low across the northern Pacific, as the longwave trough
    pivots closer to the central-northern West Coast toward the end of
    the day 1 forecast period (Sunday night). The amplification of the
    upstream trough/downstream ridge will cause the low-mid level flow
    to back s-sw once again, allowing the AR to buckle and exhibit a
    slower southward progression in the vicinity of Santa
    Cruz/Monterrey Bay by Sunday evening. During the latter half of
    the day 1 period (00-12Z Mon), the low level moisture transport
    picks up a bit (850 mb moisture flux anomalies climb to +3
    standard deviations above normal), which given the
    quasi-stationary nature of the AR with TPW values ~1.00", will
    allow for a prolonged period of high probabilities of >0.50"/hr
    rainfall rates per the HREF (between 06-12Z) within the Slight
    Risk area, which encompasses several burn scars from 2020
    (including the Hennessey scar). Given the strong upslope
    component, per the high-res CAMs localized rainfall total between
    4-8" will be possible along the windward slopes of the Santa Cruz
    and Santa Lucia Mountains.

    The secondary approaching wave late on Monday lifting toward the
    central Oregon coast, will bring a secondary moisture surge
    further north toward southwest Oregon and northern California.
    However, freezing levels will have dropped significantly resulting
    in snowfall across the higher coastal terrain, leading to highest
    potential for excessive rainfall to precisely to coastal
    locations. Some Hi-Res CAMs solutions depict some weak instability
    due to the steeper lapse rates aloft and suggest some convective
    elements particularly near Cape Mendocino. Given yesterday's
    rainfall, the Marginal Risk area will be included tightly to the
    coast.

    Hurley





    Day 2
    Valid 12Z Mon Dec 13 2021 - 12Z Tue Dec 14 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL AND SOUTHERN CALIFORNIA...

    ...California...
    Amplifying mid-upper trough and associated surface front will
    approach the central CA coast on day 2 (Mon-Mon night). Max TPW
    values remain between 0.75-1.00" (not overly anomalous for mid
    December), however low-level moisture transport remains quite
    robust as 850 mb southwesterly flow peaks between 55-65 kts and
    850-700 mb moisture flux anomalies average 4 to 4.5 standard
    deviations above normal. Guidance shows AR orientation backing
    slightly (SW to NE) on day 2 in response to the strong offshore
    height falls between 31-35N. The guidance continues to show a
    couple of QPF maxima -- one over the southern (upwind) slopes of
    the Santa Cruz mountains and another more pronounced max over the
    northern slopes of the Santa Lucia Ranges (in the vicinity of
    Pfeiffer Big Sur State Park). A few operational models show 24hr
    rainfall amounts >6" over the Northern Santa Lucias, including the
    ECMWF and GEM Regional. Hourly QPF progs from the 00Z NAM CONUS
    Nest shows a prolonged period of 0.50-0.75" hourly rainfall rates
    over these Slight Risk areas, with peak hourly rates between
    0.75-1.00" over the northern Santa Lucias after 18Z Monday. Of
    particular concern from a flash flooding and debris flow risk
    standpoint will be across the recent burn scar areas --
    specifically those from the Willow (2021), River (2020), and Dolan
    (2020) fires.=20

    Farther south, by Monday night the favorable orographic component
    will allow the heavier rates (0.50+ inch/hr) to spread across the
    Transverse Ranges and southern slopes from Point Conception east
    to Santa Barbara and areas just north of Ventura. As a result, a
    separate Slight Risk added to yesterday's Day 3 ERO will remain in
    today's Day 2 outlook.

    Hurley

    Day 3
    Valid 12Z Tue Dec 14 2021 - 12Z Wed Dec 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHWEST
    PORTIONS OF CALIFORNIA, INCLUDING THE LOS ANGELES AND SAN DIEGO
    METRO AREAS...

    ..Central-Southern California...
    Full-latitude trough/strong height falls and accompanying surface
    cold front will finally pivot through southern CA during the
    latter part of Day 3 (late Tuesday). Until then however, the AR
    and associated robust low-mid level moisture transport will shift
    southward through southwest CA, bringing a bout of heavy orograhpically-enhanced rain and mountain snows along and upwind
    of the Transverse and Peninsular ranges. Rapidly dropping snow
    levels after 00Z Wed will mitigate the flash flood and debris flow
    threat above 4000 ft, which would include several of the 2020-21
    burn scar areas. The Slight Risk from Day 2 was pulled farther
    south on Day 3, with some overlap with the Slight on Day 2 over
    the Transverse Ranges, as the AR drops across southern CA early in
    the period before accelerating south of the border after 00Z Wed.
    Hourly rainfall rates around or above 0.50" within the AR plume
    will remain possible, and as such will pose a flash flood threat
    across the LA and SD metro areas along with burn scar areas in
    nearby foothills.=20=20=20

    Hurley


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!uDjc_WrQX9rdjEmzahSF6bA1ZAYzm_BWqBL0marF87gx= hOtfmLiQ09gz9lrq1fVEfDAqv6gm$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!uDjc_WrQX9rdjEmzahSF6bA1ZAYzm_BWqBL0marF87gx= hOtfmLiQ09gz9lrq1fVEfGWytS6y$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!uDjc_WrQX9rdjEmzahSF6bA1ZAYzm_BWqBL0marF87gx= hOtfmLiQ09gz9lrq1fVEfDiwx6eM$=20


    $$




    ------------=_1639323446-34671-3306
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639323446-34671-3306--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Dec 12 19:37:25 2021
    This is a multi-part message in MIME format...

    ------------=_1639337849-34671-3435
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 121937
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    236 PM EST Sun Dec 12 2021

    Day 1
    Valid 16Z Sun Dec 12 2021 - 12Z Mon Dec 13 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL AND NORTHERN CALIFORNIA, INCLUDING SAN
    FRANCISCO AND MONTERREY BAY AREAS...

    16z update:
    ...California...
    Leading primary axis of moisture core is currently centered
    along/south of the mouth of San Francisco Bay, so have made some
    small adjustments to the northern edges of Slight Risk area for
    North Bay counties and was considering removing the Marginal Risk
    for the dry slot gap ahead of the secondary moisture surge
    associated with next shortwave/height-falls approaching by the end
    of the forecast period. However, the 12z Hi-Res CAMs show some
    timing differences that may keep central and southern Mendocino
    and Sonoma counties in play for some scattered showers/increased
    moisture flux by 13.12z to not get too precise in drawing this
    gap; even though it is more likely to be post-13.12z into the day
    2 period. Otherwise further south, the timing/placement appears
    to be on target from prior thinking with only a slight trend for
    increased rainfall rates (.5-.75"/hr) with 90%+ HREF probability
    of 24hr totals of 3" (~30% for 5"+) for the Santa Cruz Mountains;
    however, the increase is not substantial in comparison to prior
    cycles to warrant an increase in category.=20=20

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    Strong upper jet streak and vigorous shortwave energy diving
    southeastward from the Gulf of Alaska will further amplify the
    deep low across the northern Pacific, as the longwave trough
    pivots closer to the central-northern West Coast toward the end of
    the day 1 forecast period (Sunday night). The amplification of the
    upstream trough/downstream ridge will cause the low-mid level flow
    to back s-sw once again, allowing the AR to buckle and exhibit a
    slower southward progression in the vicinity of Santa
    Cruz/Monterrey Bay by Sunday evening. During the latter half of
    the day 1 period (00-12Z Mon), the low level moisture transport
    picks up a bit (850 mb moisture flux anomalies climb to +3
    standard deviations above normal), which given the
    quasi-stationary nature of the AR with TPW values ~1.00", will
    allow for a prolonged period of high probabilities of >0.50"/hr
    rainfall rates per the HREF (between 06-12Z) within the Slight
    Risk area, which encompasses several burn scars from 2020
    (including the Hennessey scar). Given the strong upslope
    component, per the high-res CAMs localized rainfall total between
    4-8" will be possible along the windward slopes of the Santa Cruz
    and Santa Lucia Mountains.

    The secondary approaching wave late on Monday lifting toward the
    central Oregon coast, will bring a secondary moisture surge
    further north toward southwest Oregon and northern California.
    However, freezing levels will have dropped significantly resulting
    in snowfall across the higher coastal terrain, leading to highest
    potential for excessive rainfall to precisely to coastal
    locations. Some Hi-Res CAMs solutions depict some weak instability
    due to the steeper lapse rates aloft and suggest some convective
    elements particularly near Cape Mendocino. Given yesterday's
    rainfall, the Marginal Risk area will be included tightly to the
    coast.

    Hurley


    Day 2
    Valid 12Z Mon Dec 13 2021 - 12Z Tue Dec 14 2021

    ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR THE BIG SUR
    COAST OF CENTRAL CALIFORNIA...

    21z update:
    ...California...
    An additional cycle of Hi-Res CAMs and HREF probabilities for the
    entirety of the Day 2 period (13.12z-14.12z) provided higher
    confidence toward upgrading a very small area of the Big Sur coast
    line where 12z HRRR, ARW, ARW2 and the HREF/NBM ensemble means
    suggest 8" totals with HREF probabilities 75% for 8"/24hr along
    the Monterey into far northwest San Luis Obispo county and near
    100% confidence in over 5", with the lowest totals at 4" by the
    UKMET/GFS (large grid scale global models). While the hi-res
    ensembles are probably skewed a bit by the 15" totals of the
    Nam-Conest, many suggest hourly rates of 1-1.25"/hr particularly
    between 15-21z when the two plumes start to merge in the vicinity
    of the Santa Lucia Mtns before starting the southward progression
    in earnest. Combine this enhancement in proximity to the 2020
    Dolan burn scar and in coordination with WFO Monterey & Oxnard, an
    upgrade to a Moderate Risk was narrow focused for this portion of
    the Big Sur coast of Central California with flash flooding and
    mudslide/rock falls becoming increasingly probable.

    As the digging shortwave associated with the secondary surge in moisture/forcing drops south, it continues to sharply amplify,
    increasing low level flow strength and taking the modest 1" total
    TPW plume tightening it increasing to 1.25" and accelerating and
    backing the winds more south-southwesterly to 45-50kts at 850mb by
    14.00z as it rounds Point Conception. This will bring more favorable/orthogonal moisture flux to the Transverse Range of
    Santa Barbara and Ventura counties with similar 1-1.25"/hr
    rates/totals. Eastward progression of the plume will limit the
    overall totals (2-5") but still continue to present a Slight Risk
    of excessive rainfall and flash flooding/debris run-off
    particularly out of the Alisal burn scar.

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    Amplifying mid-upper trough and associated surface front will
    approach the central CA coast on day 2 (Mon-Mon night). Max TPW
    values remain between 0.75-1.00" (not overly anomalous for mid
    December), however low-level moisture transport remains quite
    robust as 850 mb southwesterly flow peaks between 55-65 kts and
    850-700 mb moisture flux anomalies average 4 to 4.5 standard
    deviations above normal. Guidance shows AR orientation backing
    slightly (SW to NE) on day 2 in response to the strong offshore
    height falls between 31-35N. The guidance continues to show a
    couple of QPF maxima -- one over the southern (upwind) slopes of
    the Santa Cruz mountains and another more pronounced max over the
    northern slopes of the Santa Lucia Ranges (in the vicinity of
    Pfeiffer Big Sur State Park). A few operational models show 24hr
    rainfall amounts >6" over the Northern Santa Lucias, including the
    ECMWF and GEM Regional. Hourly QPF progs from the 00Z NAM CONUS
    Nest shows a prolonged period of 0.50-0.75" hourly rainfall rates
    over these Slight Risk areas, with peak hourly rates between
    0.75-1.00" over the northern Santa Lucias after 18Z Monday. Of
    particular concern from a flash flooding and debris flow risk
    standpoint will be across the recent burn scar areas --
    specifically those from the Willow (2021), River (2020), and Dolan
    (2020) fires.=20

    Farther south, by Monday night the favorable orographic component
    will allow the heavier rates (0.50+ inch/hr) to spread across the
    Transverse Ranges and southern slopes from Point Conception east
    to Santa Barbara and areas just north of Ventura. As a result, a
    separate Slight Risk added to yesterday's Day 3 ERO will remain in
    today's Day 2 outlook.

    Hurley

    Day 3

    The Day 3 outlook will be updated by 2030Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!oEUwYK8tLK_8musPPMt9Pfn7roYS0B2FoHDVColWS59C= ypEBqNw1eFmtBDahvzwfnmJDeozl$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!oEUwYK8tLK_8musPPMt9Pfn7roYS0B2FoHDVColWS59C= ypEBqNw1eFmtBDahvzwfnmKKQZpE$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!oEUwYK8tLK_8musPPMt9Pfn7roYS0B2FoHDVColWS59C= ypEBqNw1eFmtBDahvzwfnjgxjhGa$=20


    $$




    ------------=_1639337849-34671-3435
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639337849-34671-3435--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Dec 12 19:37:55 2021
    This is a multi-part message in MIME format...

    ------------=_1639337879-34671-3436
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 121937
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    237 PM EST Sun Dec 12 2021

    Day 1
    Valid 16Z Sun Dec 12 2021 - 12Z Mon Dec 13 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
    PORTIONS OF CENTRAL AND NORTHERN CALIFORNIA, INCLUDING SAN
    FRANCISCO AND MONTERREY BAY AREAS...

    16z update:
    ...California...
    Leading primary axis of moisture core is currently centered
    along/south of the mouth of San Francisco Bay, so have made some
    small adjustments to the northern edges of Slight Risk area for
    North Bay counties and was considering removing the Marginal Risk
    for the dry slot gap ahead of the secondary moisture surge
    associated with next shortwave/height-falls approaching by the end
    of the forecast period. However, the 12z Hi-Res CAMs show some
    timing differences that may keep central and southern Mendocino
    and Sonoma counties in play for some scattered showers/increased
    moisture flux by 13.12z to not get too precise in drawing this
    gap; even though it is more likely to be post-13.12z into the day
    2 period. Otherwise further south, the timing/placement appears
    to be on target from prior thinking with only a slight trend for
    increased rainfall rates (.5-.75"/hr) with 90%+ HREF probability
    of 24hr totals of 3" (~30% for 5"+) for the Santa Cruz Mountains;
    however, the increase is not substantial in comparison to prior
    cycles to warrant an increase in category.=20=20

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    Strong upper jet streak and vigorous shortwave energy diving
    southeastward from the Gulf of Alaska will further amplify the
    deep low across the northern Pacific, as the longwave trough
    pivots closer to the central-northern West Coast toward the end of
    the day 1 forecast period (Sunday night). The amplification of the
    upstream trough/downstream ridge will cause the low-mid level flow
    to back s-sw once again, allowing the AR to buckle and exhibit a
    slower southward progression in the vicinity of Santa
    Cruz/Monterrey Bay by Sunday evening. During the latter half of
    the day 1 period (00-12Z Mon), the low level moisture transport
    picks up a bit (850 mb moisture flux anomalies climb to +3
    standard deviations above normal), which given the
    quasi-stationary nature of the AR with TPW values ~1.00", will
    allow for a prolonged period of high probabilities of >0.50"/hr
    rainfall rates per the HREF (between 06-12Z) within the Slight
    Risk area, which encompasses several burn scars from 2020
    (including the Hennessey scar). Given the strong upslope
    component, per the high-res CAMs localized rainfall total between
    4-8" will be possible along the windward slopes of the Santa Cruz
    and Santa Lucia Mountains.

    The secondary approaching wave late on Monday lifting toward the
    central Oregon coast, will bring a secondary moisture surge
    further north toward southwest Oregon and northern California.
    However, freezing levels will have dropped significantly resulting
    in snowfall across the higher coastal terrain, leading to highest
    potential for excessive rainfall to precisely to coastal
    locations. Some Hi-Res CAMs solutions depict some weak instability
    due to the steeper lapse rates aloft and suggest some convective
    elements particularly near Cape Mendocino. Given yesterday's
    rainfall, the Marginal Risk area will be included tightly to the
    coast.

    Hurley

    Day 2
    Valid 12Z Mon Dec 13 2021 - 12Z Tue Dec 14 2021

    ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR THE BIG SUR
    COAST OF CENTRAL CALIFORNIA...

    21z update:
    ...California...
    An additional cycle of Hi-Res CAMs and HREF probabilities for the
    entirety of the Day 2 period (13.12z-14.12z) provided higher
    confidence toward upgrading a very small area of the Big Sur coast
    line where 12z HRRR, ARW, ARW2 and the HREF/NBM ensemble means
    suggest 8" totals with HREF probabilities 75% for 8"/24hr along
    the Monterey into far northwest San Luis Obispo county and near
    100% confidence in over 5", with the lowest totals at 4" by the
    UKMET/GFS (large grid scale global models). While the hi-res
    ensembles are probably skewed a bit by the 15" totals of the
    Nam-Conest, many suggest hourly rates of 1-1.25"/hr particularly
    between 15-21z when the two plumes start to merge in the vicinity
    of the Santa Lucia Mtns before starting the southward progression
    in earnest. Combine this enhancement in proximity to the 2020
    Dolan burn scar and in coordination with WFO Monterey & Oxnard, an
    upgrade to a Moderate Risk was narrow focused for this portion of
    the Big Sur coast of Central California with flash flooding and
    mudslide/rock falls becoming increasingly probable.

    As the digging shortwave associated with the secondary surge in moisture/forcing drops south, it continues to sharply amplify,
    increasing low level flow strength and taking the modest 1" total
    TPW plume tightening it increasing to 1.25" and accelerating and
    backing the winds more south-southwesterly to 45-50kts at 850mb by
    14.00z as it rounds Point Conception. This will bring more favorable/orthogonal moisture flux to the Transverse Range of
    Santa Barbara and Ventura counties with similar 1-1.25"/hr
    rates/totals. Eastward progression of the plume will limit the
    overall totals (2-5") but still continue to present a Slight Risk
    of excessive rainfall and flash flooding/debris run-off
    particularly out of the Alisal burn scar.

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    Amplifying mid-upper trough and associated surface front will
    approach the central CA coast on day 2 (Mon-Mon night). Max TPW
    values remain between 0.75-1.00" (not overly anomalous for mid
    December), however low-level moisture transport remains quite
    robust as 850 mb southwesterly flow peaks between 55-65 kts and
    850-700 mb moisture flux anomalies average 4 to 4.5 standard
    deviations above normal. Guidance shows AR orientation backing
    slightly (SW to NE) on day 2 in response to the strong offshore
    height falls between 31-35N. The guidance continues to show a
    couple of QPF maxima -- one over the southern (upwind) slopes of
    the Santa Cruz mountains and another more pronounced max over the
    northern slopes of the Santa Lucia Ranges (in the vicinity of
    Pfeiffer Big Sur State Park). A few operational models show 24hr
    rainfall amounts >6" over the Northern Santa Lucias, including the
    ECMWF and GEM Regional. Hourly QPF progs from the 00Z NAM CONUS
    Nest shows a prolonged period of 0.50-0.75" hourly rainfall rates
    over these Slight Risk areas, with peak hourly rates between
    0.75-1.00" over the northern Santa Lucias after 18Z Monday. Of
    particular concern from a flash flooding and debris flow risk
    standpoint will be across the recent burn scar areas --
    specifically those from the Willow (2021), River (2020), and Dolan
    (2020) fires.=20

    Farther south, by Monday night the favorable orographic component
    will allow the heavier rates (0.50+ inch/hr) to spread across the
    Transverse Ranges and southern slopes from Point Conception east
    to Santa Barbara and areas just north of Ventura. As a result, a
    separate Slight Risk added to yesterday's Day 3 ERO will remain in
    today's Day 2 outlook.

    Hurley

    Day 3
    Valid 12Z Tue Dec 14 2021 - 12Z Wed Dec 15 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHWEST
    PORTIONS OF CALIFORNIA, INCLUDING THE LOS ANGELES AND SAN DIEGO
    METRO AREAS...

    21z update:
    ...Southern California...
    Global guidance continues to depict a strong shortwave digging
    with strong height-falls before starting to swing negative tilt
    through southern California by 15.00z. The average to slightly
    above average moisture stream in advance of the accompanying cold
    front will see some narrowing and concentration of the deep layer
    moisture with a combination of backing low level wind response to
    the approaching shortwave while a sharp westerly push behind the
    cold combining to have nearly 4 standard deviation of moisture
    flux associated with the front as it progresses eastward at a good
    pace through the California Bight. In fact, the orientation of
    the plume initially is fairly orthogonal to the Transverse Ranges
    early in the period, but slowly veers to become modestly
    orthogonal to the Peninsular Range toward 15.00z, supporting
    .7-1"/hr rates initially (per NAM-Conest, GFS and UA WRF) before
    reducing to .5"/hr further south and east. Overall totals in the
    terrain of 3-5" (higher precipitation amounts in the highest
    elevations likely converting to snow even early) with 1-2" in the
    lower valley floors continue to support a broad Slight Risk of
    Excessive Rainfall from eastern Santa Barbara county to San Diego
    county.

    ...Northwest Arizona/Southwest Utah/Southern Nevada...
    The strength of the shortwave going negative tilt across Southern
    California into S Nevada, will support increased moisture moving
    through or over the Peninsular Range across the deserts of
    Southern California with .75" Total PWATs generally maximized over
    85-7H. Strong southerly boundary layer flow up the Lower Colorado
    River will likely increase moisture but with drier ground and
    lower atmospheric conditions in place, the strength of the flux is
    likely to generate hourly rates of .25-.5"/hr per GFS/UA WRF
    having lost some potential from sub-cloud evaporation for favored
    upslope terrain across southeast Nevada, southwest Utah and
    northwest Arizona. Even then, rapidly falling freezing levels
    would limit rainfall totals to about 1" across these areas. At
    this time, conditions are not favorable for an introduction of a
    Marginal Risk to this area but trends will be monitored especially
    with hi-res CAMs becoming available over the next few cycles.

    Gallina/Hurley


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!uX3Q0r4gM8tQu0zWeo_Hc0y3L4skvbGrBDjpSe40NHrd= Gq1F9VWFJh5O6X8XDeZkXTi8Q8tv$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!uX3Q0r4gM8tQu0zWeo_Hc0y3L4skvbGrBDjpSe40NHrd= Gq1F9VWFJh5O6X8XDeZkXQ0AsxgX$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!uX3Q0r4gM8tQu0zWeo_Hc0y3L4skvbGrBDjpSe40NHrd= Gq1F9VWFJh5O6X8XDeZkXaw95OoM$=20


    $$




    ------------=_1639337879-34671-3436
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639337879-34671-3436--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Dec 18 16:02:57 2021
    This is a multi-part message in MIME format...

    ------------=_1639843382-42186-242
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 181602
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1101 AM EST Sat Dec 18 2021

    Day 1
    Valid 16Z Sat Dec 18 2021 - 12Z Sun Dec 19 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN SOUTHEAST
    TEXAS/SOUTHWEST LOUISIANA & SOUTHEAST ALABAMA/SOUTHWEST
    GEORGIA/FLORIDA PANHANDLE...

    ...16z update...
    ...Southeast Alabama and adjacent Florida/Georgia...

    CIRA Layered Precipitable Water plots denote an anomalous pocket
    of enhanced moisture across the northeast Gulf of Mexico lifting
    northward along the western periphery of the subtropical ridge
    over the Sargasso Sea. This is particularly noticeable in the
    850-7H and 7-5H layers, this results in TPW values of 1.5-1.75". A
    slight eastward trend of the timing/placement of subtropical
    stream subtle shortwave crossing GA into SC/W NC has draped the 7H
    boundary a bit orthogonal to the moisture plume supporting some
    increased convergence, while in close proximity to higher theta-E
    source of the Gulf. As such, hi-res 12z CAM solutions (including HRRR/ARWs/Nam-Nest) suggest hourly rates of 1.75-2"/hr. 12z HREF
    demarcate an increase in heavy rainfall probabilities particularly
    across Southeast Alabama and western Panhandle in the 21-03z time
    frame. Increased deep layer steering toward the east with the
    faster progged exit of the shortwave may support short-term
    training or mergers and as a result guidance supports isolated
    2-4" totals.=20

    Limiting factor (similar to Texas) will continue to be dry soil
    conditions, as little rain has fallen over the last month ~5-15%
    of normal resulting in 0-40cm soil anomalies in 10-20% range per
    NASA SPoRT LIS product. Still, the sheer rate and less
    percolation into dry soils could result in increased runoff, and
    in conversation with the NWC, the National Water Model suggests a
    few locations of rapid onset flooding are possible. As such have
    introduced a small Marginal Risk of Excessive Rainfall to account
    for this potential.

    ...Southeast Texas/Southwest Louisiana...
    12z Hi-Res CAMs continue to hone in on pre-frontal slow moving
    convection developing in higher theta-e, moisture surge off the
    western Gulf low level flow with potential for increased rain
    rates of 2-2.5"/hr. The greater concern is as the frontal
    convection progresses southward, cell mergers and increased
    duration for intense rates could pose localized 3-4"+ totals,
    particularly in the vicinity of Metro Houston. 12z HREF
    probabilities continue to steadily increase and provide confidence
    for excessive rainfall with 3"/3hr probabilities at 50% in the
    18-00z time frame. Thereafter, the front should progress
    offshore. As such, have introduced a small Slight Risk generally
    centered over the Metro.


    ...Central Oregon Coastal Range...
    A solid but not highly anomalous Atmospheric river is currently in
    progress over the Olympic Range of western Washington into the
    Northern Cascades. Integrated Vapor Transport (IVT) values of 750
    kg/m/s are solid going into Washington, but given the shortwave
    continues to be progressing tracking through Washington into the
    northern US Rockies/southern Canadian Rockies by 12z, the
    magnitudes of higher QPF are generally above freezing levels
    resulting in heavier snow than potential excessive
    rainfall/run-off.=20=20

    However, as the front sags south into northern and central Coastal
    Range of Oregon, the plume starts to stall under weakening
    influence of the exiting wave but strengthening influence of the strengthening/deepening upstream wave and increased southerly
    flow. Winds will slacken and IVT values will drop to about
    400-500 kg/m/s as PW values drop to below 1". Rain rates will
    also be below .5"/hr but still support longer duration moderate
    rainfall with totals of 1-2.5" in the Coastal Range (below
    freezing levels) prior to 19.12z. AHPS precipitation anomalies
    are above average but soil conditions are normal per NASA SPoRT
    LIS 0-40cm product. So, at this time have not introduced a
    Marginal Risk of excessive rainfall, though it is close, but in
    continuation into the D2 period, it will need to be further
    evaluated.=20

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    ...Southeast Texas/Southwest Louisiana...
    A cold front will sweep southeast quickly in the western Gulf
    Coast region today, likely moving offshore of Texas by 00Z, and
    Louisiana shortly thereafter. Therefore, the threat of heavy
    rainfall from convection along and ahead of the front will be
    concentrated in the first half of the forecast period, although it
    should be focused most acutely around the time of the frontal
    passage. The environment will be generally supportive of high
    instantaneous rain rates and organized convective lines and
    clusters, with precipitable water values around 1.6 to 1.8 inches
    (above the 95th percentile for December) and MUCAPE around
    1000-1500 j/kg (above the 90th percentile for December). Indeed,
    multiple HREF members show 2+ inch per hour rain rates, and the
    06Z HRRR indicates 15-minute rain rates potentially reaching 1
    inch in the strongest convection.

    The main limiting factors for flash flood impacts will be the
    progressive nature of the front, which should limit the residence
    time of intense rain in any one location, and the dry antecedent
    conditions with 30-day rainfall around half the average value at a
    normally drier time of year. Therefore, the most likely location
    for impacts would be in any urbanized areas, particularly the
    Houston metro area, where even short bursts of very intense
    rainfall could produce excessive runoff. However, given the
    aforementioned limiting factors, the Marginal Risk that was
    already in effect has been maintained. If confidence grows in
    heavy rain rates being sustained for more than an hour in the
    Houston metro area, it's possible a localized upgrade to Slight
    Risk could be warranted.

    Lamers


    Day 2
    Valid 12Z Sun Dec 19 2021 - 12Z Mon Dec 20 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Lamers

    Day 3
    Valid 12Z Mon Dec 20 2021 - 12Z Tue Dec 21 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Lamers


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!t2Mld_m89doykJLTiSkmJDV7LDyr-ZoW93DMapfs6ppk= 5s31h67kXvnSzBlX5hWOtFLLpbHq$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!t2Mld_m89doykJLTiSkmJDV7LDyr-ZoW93DMapfs6ppk= 5s31h67kXvnSzBlX5hWOtLDvl-1J$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!t2Mld_m89doykJLTiSkmJDV7LDyr-ZoW93DMapfs6ppk= 5s31h67kXvnSzBlX5hWOtBIZaNDf$=20


    $$




    ------------=_1639843382-42186-242
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639843382-42186-242--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Dec 18 16:03:58 2021
    This is a multi-part message in MIME format...

    ------------=_1639843442-42186-243
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 181603
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1103 AM EST Sat Dec 18 2021

    Day 1
    Valid 16Z Sat Dec 18 2021 - 12Z Sun Dec 19 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN SOUTHEAST
    TEXAS...

    ...16z update...
    ...Southeast Alabama and adjacent Florida/Georgia...

    CIRA Layered Precipitable Water plots denote an anomalous pocket
    of enhanced moisture across the northeast Gulf of Mexico lifting
    northward along the western periphery of the subtropical ridge
    over the Sargasso Sea. This is particularly noticeable in the
    850-7H and 7-5H layers, this results in TPW values of 1.5-1.75". A
    slight eastward trend of the timing/placement of subtropical
    stream subtle shortwave crossing GA into SC/W NC has draped the 7H
    boundary a bit orthogonal to the moisture plume supporting some
    increased convergence, while in close proximity to higher theta-E
    source of the Gulf. As such, hi-res 12z CAM solutions (including HRRR/ARWs/Nam-Nest) suggest hourly rates of 1.75-2"/hr. 12z HREF
    demarcate an increase in heavy rainfall probabilities particularly
    across Southeast Alabama and western Panhandle in the 21-03z time
    frame. Increased deep layer steering toward the east with the
    faster progged exit of the shortwave may support short-term
    training or mergers and as a result guidance supports isolated
    2-4" totals.=20

    Limiting factor (similar to Texas) will continue to be dry soil
    conditions, as little rain has fallen over the last month ~5-15%
    of normal resulting in 0-40cm soil anomalies in 10-20% range per
    NASA SPoRT LIS product. Still, the sheer rate and less
    percolation into dry soils could result in increased runoff, and
    in conversation with the NWC, the National Water Model suggests a
    few locations of rapid onset flooding are possible. As such have
    introduced a small Marginal Risk of Excessive Rainfall to account
    for this potential.

    ...Southeast Texas/Southwest Louisiana...
    12z Hi-Res CAMs continue to hone in on pre-frontal slow moving
    convection developing in higher theta-e, moisture surge off the
    western Gulf low level flow with potential for increased rain
    rates of 2-2.5"/hr. The greater concern is as the frontal
    convection progresses southward, cell mergers and increased
    duration for intense rates could pose localized 3-4"+ totals,
    particularly in the vicinity of Metro Houston. 12z HREF
    probabilities continue to steadily increase and provide confidence
    for excessive rainfall with 3"/3hr probabilities at 50% in the
    18-00z time frame. Thereafter, the front should progress
    offshore. As such, have introduced a small Slight Risk generally
    centered over the Metro.


    ...Central Oregon Coastal Range...
    A solid but not highly anomalous Atmospheric river is currently in
    progress over the Olympic Range of western Washington into the
    Northern Cascades. Integrated Vapor Transport (IVT) values of 750
    kg/m/s are solid going into Washington, but given the shortwave
    continues to be progressing tracking through Washington into the
    northern US Rockies/southern Canadian Rockies by 12z, the
    magnitudes of higher QPF are generally above freezing levels
    resulting in heavier snow than potential excessive
    rainfall/run-off.=20=20

    However, as the front sags south into northern and central Coastal
    Range of Oregon, the plume starts to stall under weakening
    influence of the exiting wave but strengthening influence of the strengthening/deepening upstream wave and increased southerly
    flow. Winds will slacken and IVT values will drop to about
    400-500 kg/m/s as PW values drop to below 1". Rain rates will
    also be below .5"/hr but still support longer duration moderate
    rainfall with totals of 1-2.5" in the Coastal Range (below
    freezing levels) prior to 19.12z. AHPS precipitation anomalies
    are above average but soil conditions are normal per NASA SPoRT
    LIS 0-40cm product. So, at this time have not introduced a
    Marginal Risk of excessive rainfall, though it is close, but in
    continuation into the D2 period, it will need to be further
    evaluated.=20

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    ...Southeast Texas/Southwest Louisiana...
    A cold front will sweep southeast quickly in the western Gulf
    Coast region today, likely moving offshore of Texas by 00Z, and
    Louisiana shortly thereafter. Therefore, the threat of heavy
    rainfall from convection along and ahead of the front will be
    concentrated in the first half of the forecast period, although it
    should be focused most acutely around the time of the frontal
    passage. The environment will be generally supportive of high
    instantaneous rain rates and organized convective lines and
    clusters, with precipitable water values around 1.6 to 1.8 inches
    (above the 95th percentile for December) and MUCAPE around
    1000-1500 j/kg (above the 90th percentile for December). Indeed,
    multiple HREF members show 2+ inch per hour rain rates, and the
    06Z HRRR indicates 15-minute rain rates potentially reaching 1
    inch in the strongest convection.

    The main limiting factors for flash flood impacts will be the
    progressive nature of the front, which should limit the residence
    time of intense rain in any one location, and the dry antecedent
    conditions with 30-day rainfall around half the average value at a
    normally drier time of year. Therefore, the most likely location
    for impacts would be in any urbanized areas, particularly the
    Houston metro area, where even short bursts of very intense
    rainfall could produce excessive runoff. However, given the
    aforementioned limiting factors, the Marginal Risk that was
    already in effect has been maintained. If confidence grows in
    heavy rain rates being sustained for more than an hour in the
    Houston metro area, it's possible a localized upgrade to Slight
    Risk could be warranted.

    Lamers


    Day 2
    Valid 12Z Sun Dec 19 2021 - 12Z Mon Dec 20 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Lamers

    Day 3
    Valid 12Z Mon Dec 20 2021 - 12Z Tue Dec 21 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Lamers


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!smF-iXgjIGpp0Nzbl-MNGTg_j4y4zwy20aFJLtQGJUBQ= czaPQ1EcHtSwIe8AT2iRLhmpjnxA$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!smF-iXgjIGpp0Nzbl-MNGTg_j4y4zwy20aFJLtQGJUBQ= czaPQ1EcHtSwIe8AT2iRLo8AwHF-$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!smF-iXgjIGpp0Nzbl-MNGTg_j4y4zwy20aFJLtQGJUBQ= czaPQ1EcHtSwIe8AT2iRLkt7u8py$=20


    $$




    ------------=_1639843442-42186-243
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639843442-42186-243--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Dec 18 18:46:30 2021
    This is a multi-part message in MIME format...

    ------------=_1639853193-42186-294
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 181846
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    145 PM EST Sat Dec 18 2021

    Day 1
    Valid 16Z Sat Dec 18 2021 - 12Z Sun Dec 19 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN SOUTHEAST
    TEXAS...

    ...16z update...
    ...Southeast Alabama and adjacent Florida/Georgia...

    CIRA Layered Precipitable Water plots denote an anomalous pocket
    of enhanced moisture across the northeast Gulf of Mexico lifting
    northward along the western periphery of the subtropical ridge
    over the Sargasso Sea. This is particularly noticeable in the
    850-7H and 7-5H layers, this results in TPW values of 1.5-1.75". A
    slight eastward trend of the timing/placement of subtropical
    stream subtle shortwave crossing GA into SC/W NC has draped the 7H
    boundary a bit orthogonal to the moisture plume supporting some
    increased convergence, while in close proximity to higher theta-E
    source of the Gulf. As such, hi-res 12z CAM solutions (including HRRR/ARWs/Nam-Nest) suggest hourly rates of 1.75-2"/hr. 12z HREF
    demarcate an increase in heavy rainfall probabilities particularly
    across Southeast Alabama and western Panhandle in the 21-03z time
    frame. Increased deep layer steering toward the east with the
    faster progged exit of the shortwave may support short-term
    training or mergers and as a result guidance supports isolated
    2-4" totals.=20

    Limiting factor (similar to Texas) will continue to be dry soil
    conditions, as little rain has fallen over the last month ~5-15%
    of normal resulting in 0-40cm soil anomalies in 10-20% range per
    NASA SPoRT LIS product. Still, the sheer rate and less
    percolation into dry soils could result in increased runoff, and
    in conversation with the NWC, the National Water Model suggests a
    few locations of rapid onset flooding are possible. As such have
    introduced a small Marginal Risk of Excessive Rainfall to account
    for this potential.

    ...Southeast Texas/Southwest Louisiana...
    12z Hi-Res CAMs continue to hone in on pre-frontal slow moving
    convection developing in higher theta-e, moisture surge off the
    western Gulf low level flow with potential for increased rain
    rates of 2-2.5"/hr. The greater concern is as the frontal
    convection progresses southward, cell mergers and increased
    duration for intense rates could pose localized 3-4"+ totals,
    particularly in the vicinity of Metro Houston. 12z HREF
    probabilities continue to steadily increase and provide confidence
    for excessive rainfall with 3"/3hr probabilities at 50% in the
    18-00z time frame. Thereafter, the front should progress
    offshore. As such, have introduced a small Slight Risk generally
    centered over the Metro.


    ...Central Oregon Coastal Range...
    A solid but not highly anomalous Atmospheric river is currently in
    progress over the Olympic Range of western Washington into the
    Northern Cascades. Integrated Vapor Transport (IVT) values of 750
    kg/m/s are solid going into Washington, but given the shortwave
    continues to be progressing tracking through Washington into the
    northern US Rockies/southern Canadian Rockies by 12z, the
    magnitudes of higher QPF are generally above freezing levels
    resulting in heavier snow than potential excessive
    rainfall/run-off.=20=20

    However, as the front sags south into northern and central Coastal
    Range of Oregon, the plume starts to stall under weakening
    influence of the exiting wave but strengthening influence of the strengthening/deepening upstream wave and increased southerly
    flow. Winds will slacken and IVT values will drop to about
    400-500 kg/m/s as PW values drop to below 1". Rain rates will
    also be below .5"/hr but still support longer duration moderate
    rainfall with totals of 1-2.5" in the Coastal Range (below
    freezing levels) prior to 19.12z. AHPS precipitation anomalies
    are above average but soil conditions are normal per NASA SPoRT
    LIS 0-40cm product. So, at this time have not introduced a
    Marginal Risk of excessive rainfall, though it is close, but in
    continuation into the D2 period, it will need to be further
    evaluated.=20

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    ...Southeast Texas/Southwest Louisiana...
    A cold front will sweep southeast quickly in the western Gulf
    Coast region today, likely moving offshore of Texas by 00Z, and
    Louisiana shortly thereafter. Therefore, the threat of heavy
    rainfall from convection along and ahead of the front will be
    concentrated in the first half of the forecast period, although it
    should be focused most acutely around the time of the frontal
    passage. The environment will be generally supportive of high
    instantaneous rain rates and organized convective lines and
    clusters, with precipitable water values around 1.6 to 1.8 inches
    (above the 95th percentile for December) and MUCAPE around
    1000-1500 j/kg (above the 90th percentile for December). Indeed,
    multiple HREF members show 2+ inch per hour rain rates, and the
    06Z HRRR indicates 15-minute rain rates potentially reaching 1
    inch in the strongest convection.

    The main limiting factors for flash flood impacts will be the
    progressive nature of the front, which should limit the residence
    time of intense rain in any one location, and the dry antecedent
    conditions with 30-day rainfall around half the average value at a
    normally drier time of year. Therefore, the most likely location
    for impacts would be in any urbanized areas, particularly the
    Houston metro area, where even short bursts of very intense
    rainfall could produce excessive runoff. However, given the
    aforementioned limiting factors, the Marginal Risk that was
    already in effect has been maintained. If confidence grows in
    heavy rain rates being sustained for more than an hour in the
    Houston metro area, it's possible a localized upgrade to Slight
    Risk could be warranted.

    Lamers


    Day 2
    Valid 12Z Sun Dec 19 2021 - 12Z Mon Dec 20 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG THE
    CENTRAL OREGON COASTAL RANGES...

    At the start of the forecast period, 19.12z, the tail end of the
    cold front from a quickly exiting shortwave across the US/Canadian
    boarder Rockies will have started to stall into a stationary front
    crossing the Central Oregon coast between Tillamook and N Coos
    county. Deep layer moisture westerly flow will be slacking a bit,
    bringing Integrated Vapor Transport (IVT) values to weak to modest
    levels around 400-500 kg/m/s. Broadening shield of modest rain
    rates of .1-.2"/hr will exist across much of the area of concern,
    though rates of .25-.33"/hr are possible with weak vertical
    convective development due to proximity to the front itself.=20
    However, large scale troughing further southwest will rapidly
    deepen a surface cyclone, but will shed a weak mid-level shortwave
    feature northeast toward the OR coast. This will spur weak
    cyclogenesis and back and strengthen low level flow from 30 to 50+
    kts by early morning. This increase in flow will bring higher
    total PWats back to near 1" and IVT values in the 750 kg/m/s range
    per GEFS/ECENS members. The front will lift northward as a warm
    front, but given overall depth of mid-level steering flow, some
    shallow convective elements have the potential to intersect the
    coast in similar placement to heavier rainfall from the Day 1 time
    period (18.12z-19.12z) where 1-2.5" are expected to fall.=20

    Steadily increasing rain-rates up to .5"/hr are possible
    particularly between 18z and 03z for the central Oregon Coastal
    Range. HREF probabilities reach peaks of 50-60% in this time frame
    for rates of .33"/hr or 1"/3hr. As the wave moves through, global
    guidance (NAM, GFS, UKMET, CMC, ECMWF) suggest and additional 2-4"
    bringing 48hr totals across the region to 3-6". Hi-Res CAMs, to
    be expected, are a tad higher for south-southwestward facing
    orography. As such. As noted in Day 1 ERO discussion, the soil
    conditions are generally average, but the two day combination has
    some potential for excessive rainfall/flooding with
    mudslides/debris flows particularly near burn scars. As such, a
    Marginal Risk of Excessive Rainfall was introduced, with
    coordination from local forecast offices, for the central Oregon
    coastal region.

    While the strength of the moisture flux, wind flow resulting in
    orographic ascent is much lower across the lower slopes of the
    Oregon Cascade region, increased overall rainfall totals
    throughout the 48hr period to 2-4", perhaps higher across numerous
    large burn scars from the 2020 and 2021 seasons resulted in
    expanding the Marginal Risk across to the lower slopes, below
    freezing levels in the central Oregon Cascade Range.


    Gallina




    Day 3

    The Day 3 outlook will be updated by 2030Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!s8WErSLQLATtBgiwq2n_fQ6NJUj2PaN3UK8u_D2qI5aY= oTpKHrMBIyDijZoaYlLUhYpiQxfQ$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!s8WErSLQLATtBgiwq2n_fQ6NJUj2PaN3UK8u_D2qI5aY= oTpKHrMBIyDijZoaYlLUhXWRQEZz$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!s8WErSLQLATtBgiwq2n_fQ6NJUj2PaN3UK8u_D2qI5aY= oTpKHrMBIyDijZoaYlLUhVOw3EpM$=20


    $$




    ------------=_1639853193-42186-294
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639853193-42186-294--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Dec 18 18:47:28 2021
    This is a multi-part message in MIME format...

    ------------=_1639853253-42186-295
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 181847
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    146 PM EST Sat Dec 18 2021

    Day 1
    Valid 16Z Sat Dec 18 2021 - 12Z Sun Dec 19 2021

    ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN SOUTHEAST
    TEXAS...

    ...16z update...
    ...Southeast Alabama and adjacent Florida/Georgia...

    CIRA Layered Precipitable Water plots denote an anomalous pocket
    of enhanced moisture across the northeast Gulf of Mexico lifting
    northward along the western periphery of the subtropical ridge
    over the Sargasso Sea. This is particularly noticeable in the
    850-7H and 7-5H layers, this results in TPW values of 1.5-1.75". A
    slight eastward trend of the timing/placement of subtropical
    stream subtle shortwave crossing GA into SC/W NC has draped the 7H
    boundary a bit orthogonal to the moisture plume supporting some
    increased convergence, while in close proximity to higher theta-E
    source of the Gulf. As such, hi-res 12z CAM solutions (including HRRR/ARWs/Nam-Nest) suggest hourly rates of 1.75-2"/hr. 12z HREF
    demarcate an increase in heavy rainfall probabilities particularly
    across Southeast Alabama and western Panhandle in the 21-03z time
    frame. Increased deep layer steering toward the east with the
    faster progged exit of the shortwave may support short-term
    training or mergers and as a result guidance supports isolated
    2-4" totals.=20

    Limiting factor (similar to Texas) will continue to be dry soil
    conditions, as little rain has fallen over the last month ~5-15%
    of normal resulting in 0-40cm soil anomalies in 10-20% range per
    NASA SPoRT LIS product. Still, the sheer rate and less
    percolation into dry soils could result in increased runoff, and
    in conversation with the NWC, the National Water Model suggests a
    few locations of rapid onset flooding are possible. As such have
    introduced a small Marginal Risk of Excessive Rainfall to account
    for this potential.

    ...Southeast Texas/Southwest Louisiana...
    12z Hi-Res CAMs continue to hone in on pre-frontal slow moving
    convection developing in higher theta-e, moisture surge off the
    western Gulf low level flow with potential for increased rain
    rates of 2-2.5"/hr. The greater concern is as the frontal
    convection progresses southward, cell mergers and increased
    duration for intense rates could pose localized 3-4"+ totals,
    particularly in the vicinity of Metro Houston. 12z HREF
    probabilities continue to steadily increase and provide confidence
    for excessive rainfall with 3"/3hr probabilities at 50% in the
    18-00z time frame. Thereafter, the front should progress
    offshore. As such, have introduced a small Slight Risk generally
    centered over the Metro.


    ...Central Oregon Coastal Range...
    A solid but not highly anomalous Atmospheric river is currently in
    progress over the Olympic Range of western Washington into the
    Northern Cascades. Integrated Vapor Transport (IVT) values of 750
    kg/m/s are solid going into Washington, but given the shortwave
    continues to be progressing tracking through Washington into the
    northern US Rockies/southern Canadian Rockies by 12z, the
    magnitudes of higher QPF are generally above freezing levels
    resulting in heavier snow than potential excessive
    rainfall/run-off.=20=20

    However, as the front sags south into northern and central Coastal
    Range of Oregon, the plume starts to stall under weakening
    influence of the exiting wave but strengthening influence of the strengthening/deepening upstream wave and increased southerly
    flow. Winds will slacken and IVT values will drop to about
    400-500 kg/m/s as PW values drop to below 1". Rain rates will
    also be below .5"/hr but still support longer duration moderate
    rainfall with totals of 1-2.5" in the Coastal Range (below
    freezing levels) prior to 19.12z. AHPS precipitation anomalies
    are above average but soil conditions are normal per NASA SPoRT
    LIS 0-40cm product. So, at this time have not introduced a
    Marginal Risk of excessive rainfall, though it is close, but in
    continuation into the D2 period, it will need to be further
    evaluated.=20

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~~
    ...Southeast Texas/Southwest Louisiana...
    A cold front will sweep southeast quickly in the western Gulf
    Coast region today, likely moving offshore of Texas by 00Z, and
    Louisiana shortly thereafter. Therefore, the threat of heavy
    rainfall from convection along and ahead of the front will be
    concentrated in the first half of the forecast period, although it
    should be focused most acutely around the time of the frontal
    passage. The environment will be generally supportive of high
    instantaneous rain rates and organized convective lines and
    clusters, with precipitable water values around 1.6 to 1.8 inches
    (above the 95th percentile for December) and MUCAPE around
    1000-1500 j/kg (above the 90th percentile for December). Indeed,
    multiple HREF members show 2+ inch per hour rain rates, and the
    06Z HRRR indicates 15-minute rain rates potentially reaching 1
    inch in the strongest convection.

    The main limiting factors for flash flood impacts will be the
    progressive nature of the front, which should limit the residence
    time of intense rain in any one location, and the dry antecedent
    conditions with 30-day rainfall around half the average value at a
    normally drier time of year. Therefore, the most likely location
    for impacts would be in any urbanized areas, particularly the
    Houston metro area, where even short bursts of very intense
    rainfall could produce excessive runoff. However, given the
    aforementioned limiting factors, the Marginal Risk that was
    already in effect has been maintained. If confidence grows in
    heavy rain rates being sustained for more than an hour in the
    Houston metro area, it's possible a localized upgrade to Slight
    Risk could be warranted.

    Lamers


    Day 2
    Valid 12Z Sun Dec 19 2021 - 12Z Mon Dec 20 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG THE
    CENTRAL OREGON COASTAL RANGES...

    At the start of the forecast period, 19.12z, the tail end of the
    cold front from a quickly exiting shortwave across the US/Canadian
    boarder Rockies will have started to stall into a stationary front
    crossing the Central Oregon coast between Tillamook and N Coos
    county. Deep layer moisture westerly flow will be slacking a bit,
    bringing Integrated Vapor Transport (IVT) values to weak to modest
    levels around 400-500 kg/m/s. Broadening shield of modest rain
    rates of .1-.2"/hr will exist across much of the area of concern,
    though rates of .25-.33"/hr are possible with weak vertical
    convective development due to proximity to the front itself.=20
    However, large scale troughing further southwest will rapidly
    deepen a surface cyclone, but will shed a weak mid-level shortwave
    feature northeast toward the OR coast. This will spur weak
    cyclogenesis and back and strengthen low level flow from 30 to 50+
    kts by early morning. This increase in flow will bring higher
    total PWats back to near 1" and IVT values in the 750 kg/m/s range
    per GEFS/ECENS members. The front will lift northward as a warm
    front, but given overall depth of mid-level steering flow, some
    shallow convective elements have the potential to intersect the
    coast in similar placement to heavier rainfall from the Day 1 time
    period (18.12z-19.12z) where 1-2.5" are expected to fall.=20

    Steadily increasing rain-rates up to .5"/hr are possible
    particularly between 18z and 03z for the central Oregon Coastal
    Range. HREF probabilities reach peaks of 50-60% in this time frame
    for rates of .33"/hr or 1"/3hr. As the wave moves through, global
    guidance (NAM, GFS, UKMET, CMC, ECMWF) suggest and additional 2-4"
    bringing 48hr totals across the region to 3-6". Hi-Res CAMs, to
    be expected, are a tad higher for south-southwestward facing
    orography. As such. As noted in Day 1 ERO discussion, the soil
    conditions are generally average, but the two day combination has
    some potential for excessive rainfall/flooding with
    mudslides/debris flows particularly near burn scars. As such, a
    Marginal Risk of Excessive Rainfall was introduced, with
    coordination from local forecast offices, for the central Oregon
    coastal region.

    While the strength of the moisture flux, wind flow resulting in
    orographic ascent is much lower across the lower slopes of the
    Oregon Cascade region, increased overall rainfall totals
    throughout the 48hr period to 2-4", perhaps higher across numerous
    large burn scars from the 2020 and 2021 seasons resulted in
    expanding the Marginal Risk across to the lower slopes, below
    freezing levels in the central Oregon Cascade Range.

    Gallina


    Day 3
    Valid 12Z Mon Dec 20 2021 - 12Z Tue Dec 21 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Gallina


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!qPawITrikHMPHsW40W9u9JNFquA6dts9vKPw0wujtgF5= i1OJHSynDw39eLmts39x25qaHck8$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!qPawITrikHMPHsW40W9u9JNFquA6dts9vKPw0wujtgF5= i1OJHSynDw39eLmts39x25ypyxLf$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!qPawITrikHMPHsW40W9u9JNFquA6dts9vKPw0wujtgF5= i1OJHSynDw39eLmts39x2x1p8D2L$=20


    $$




    ------------=_1639853253-42186-295
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639853253-42186-295--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Dec 19 15:38:40 2021
    This is a multi-part message in MIME format...

    ------------=_1639928324-42186-839
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 191538
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    1037 AM EST Sun Dec 19 2021

    Day 1
    Valid 12Z Sun Dec 19 2021 - 12Z Mon Dec 20 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN WESTERN
    OREGON...

    16z update:
    Recent observations along the central Oregon coastal range
    indicate .25-.33"/hr rates. 12z Hi-Res CAMs continue to suggest an
    additional 2-3" are possible across the Marginal Risk and HREF
    probabilities continue to show similar rates peaking through 00z
    before deep layer flow backs to reduce best favorable orientation.
    As such, no substantive changes were made to the risk area.

    Gallina


    ...Western Oregon...

    Portions of western Oregon will be in the midst of a heavy
    rainfall event at the beginning of the period, with southwesterly
    onshore flow through much of the depth of the troposphere.
    Important changes in the flow pattern will take place during the
    forecast period as a trough digs sharply off the West Coast and
    begins to close off a deep low around 38N/135W. The ribbon of
    modest IVT (about 500 kg/m/s) will be in the process of weakening
    around the start of the forecast period, before the flow backs (to
    a more southerly direction) and increases once more in the
    afternoon and evening hours (albeit mostly offshore). The end
    result will be weaker flow that is less favorably positioned to
    intercept the north-south mountain ranges in an orthogonal fashion
    (thereby maximizing orographic lift on a larger scale).
    Furthermore, other factors that could compensate somewhat for
    weaker low-mid tropospheric winds, such as highly anomalous
    atmospheric moisture or instability, are not really present
    either. Indeed, 00Z HREF probabilities of even 0.5 inch per hour
    rainfall rates are negligible for the entire forecast period.
    Therefore, the threat of impactful heavy rain should be somewhat
    localized -- where orographic ascent is more favorably maximized
    with the wind shifts, or perhaps with some of the large burn scars
    in the area. And with a threat of localized impacts, the Marginal
    Risk across the area was maintained.

    Lamers


    Day 2
    Valid 12Z Mon Dec 20 2021 - 12Z Tue Dec 21 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Lamers




    Day 3
    Valid 12Z Tue Dec 21 2021 - 12Z Wed Dec 22 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    ...Southern Alabama, Southern Georgia, and the Florida Panhandle...
    No risk area was outlined at the moment for Tuesday and Tuesday
    Night along the Eastern Gulf Coast. Although heavy rain is in the
    forecast, QPF is currently not particularly anomalous, and even
    90th percentile PQPF values do not rise to even a 1-2 year average
    annual recurrence interval. Nevertheless, there are signals for
    somewhat anomalous available moisture (PWATs around the 90th
    percentile for December), some instability (MUCAPE 200-500 j/kg),
    and persistent forcing with a surface low forming in the eastern
    Gulf and slowly shifting northeast. This could theoretically
    support some localized heavy rain rates around or just over 1 inch
    per hour in areas of persistent low-level convergence (that would
    focus more organized convective clusters). This area will be
    monitored for future outlooks, as there is still considerable
    model spread even on basic facets of the scenario like placement
    of the axis of heavy rain.

    Lamers


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!s2LeGUAnkLXjWWbLvKbDyaRKW75HmaDqd0rFqqu8czCU= ge2CqQyYXTKBKNVY6GBhfGLSM9ij$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!s2LeGUAnkLXjWWbLvKbDyaRKW75HmaDqd0rFqqu8czCU= ge2CqQyYXTKBKNVY6GBhfBatLNwX$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!s2LeGUAnkLXjWWbLvKbDyaRKW75HmaDqd0rFqqu8czCU= ge2CqQyYXTKBKNVY6GBhfIBNBekr$=20


    $$




    ------------=_1639928324-42186-839
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639928324-42186-839--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Dec 19 19:32:14 2021
    This is a multi-part message in MIME format...

    ------------=_1639942342-42186-910
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 191932
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    231 PM EST Sun Dec 19 2021

    Day 1
    Valid 16Z Sun Dec 19 2021 - 12Z Mon Dec 20 2021

    ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN WESTERN
    OREGON...

    16z update:
    Recent observations along the central Oregon coastal range
    indicate .25-.33"/hr rates. 12z Hi-Res CAMs continue to suggest an
    additional 2-3" are possible across the Marginal Risk and HREF
    probabilities continue to show similar rates peaking through 00z
    before deep layer flow backs to reduce best favorable orientation.
    As such, no substantive changes were made to the risk area.

    Gallina


    ...Western Oregon...

    Portions of western Oregon will be in the midst of a heavy
    rainfall event at the beginning of the period, with southwesterly
    onshore flow through much of the depth of the troposphere.
    Important changes in the flow pattern will take place during the
    forecast period as a trough digs sharply off the West Coast and
    begins to close off a deep low around 38N/135W. The ribbon of
    modest IVT (about 500 kg/m/s) will be in the process of weakening
    around the start of the forecast period, before the flow backs (to
    a more southerly direction) and increases once more in the
    afternoon and evening hours (albeit mostly offshore). The end
    result will be weaker flow that is less favorably positioned to
    intercept the north-south mountain ranges in an orthogonal fashion
    (thereby maximizing orographic lift on a larger scale).
    Furthermore, other factors that could compensate somewhat for
    weaker low-mid tropospheric winds, such as highly anomalous
    atmospheric moisture or instability, are not really present
    either. Indeed, 00Z HREF probabilities of even 0.5 inch per hour
    rainfall rates are negligible for the entire forecast period.
    Therefore, the threat of impactful heavy rain should be somewhat
    localized -- where orographic ascent is more favorably maximized
    with the wind shifts, or perhaps with some of the large burn scars
    in the area. And with a threat of localized impacts, the Marginal
    Risk across the area was maintained.

    Lamers


    Day 2
    Valid 12Z Mon Dec 20 2021 - 12Z Tue Dec 21 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Gallina




    Day 3
    Valid 12Z Tue Dec 21 2021 - 12Z Wed Dec 22 2021

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    21z update:

    ...Southern Georgia, and the Florida Panhandle...
    Global guidance continues to depict a very similar evolution with
    respect to the surface cyclone and placement of potentially
    excessive rainfall swath. Synoptically, the strong 1-2 standard
    deviation shortwave, sharpens into the eastern Gulf reaching 90 to
    95th percentiles for the time of year for negative anomalies.=20
    This produces/maintains a strong low level cyclone that is
    expected to have strong convection within deep layer moisture
    convergence along the northern deformation zone of the cyclone.=20
    Deep warm Gulf waters produce ample instability, but as the depth
    reduces and reaches the shelf, rain-rates are expected to reduce
    and be driven mainly by any retained weak to modest mid-level
    instability along the down-shear deformation zone, which given
    cell motions/cyclone track could provide a narrow corridor for
    training and enhanced rainfall totals.=20

    Unfortunately, the guidance continues to waver and be generally
    inconsistent where the deformation axis aligns even at 48 to 72hrs
    out. Generally, this could be as far north as AL/GA/FL border
    intersection into central GA or as far south as the I-4 corridor,
    with the average generally crossing across the Big Bend of Florida
    north of the mouth of the Suwanee. This area and into the
    Okefenokee Swamp generally has favorable soils to handle even
    prolonged moderate rain rates and has been running about average
    to slightly below average for precipitation and soil saturation,
    so will maintain a less than 5 percent probability of FFG, until
    guidance settles on a location or rainfall rates/totals increase.

    Gallina


    Prior Discussion
    ~~~~~~~~~~~~~~~~~~
    No risk area was outlined at the moment for Tuesday and Tuesday
    Night along the Eastern Gulf Coast. Although heavy rain is in the
    forecast, QPF is currently not particularly anomalous, and even
    90th percentile PQPF values do not rise to even a 1-2 year average
    annual recurrence interval. Nevertheless, there are signals for
    somewhat anomalous available moisture (PWATs around the 90th
    percentile for December), some instability (MUCAPE 200-500 j/kg),
    and persistent forcing with a surface low forming in the eastern
    Gulf and slowly shifting northeast. This could theoretically
    support some localized heavy rain rates around or just over 1 inch
    per hour in areas of persistent low-level convergence (that would
    focus more organized convective clusters). This area will be
    monitored for future outlooks, as there is still considerable
    model spread even on basic facets of the scenario like placement
    of the axis of heavy rain.

    Lamers


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!rz1TPwX9lrCtr3VFVLYFa86klWoyVg_Dk6TmH72kSmYJ= rROQwjbfjZuXcTWz4yCVWMD4DPeF$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!rz1TPwX9lrCtr3VFVLYFa86klWoyVg_Dk6TmH72kSmYJ= rROQwjbfjZuXcTWz4yCVWETGeRLR$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!rz1TPwX9lrCtr3VFVLYFa86klWoyVg_Dk6TmH72kSmYJ= rROQwjbfjZuXcTWz4yCVWMmilXUH$=20


    $$




    ------------=_1639942342-42186-910
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1639942342-42186-910--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Dec 28 07:53:00 2021
    This is a multi-part message in MIME format...

    ------------=_1640677985-57364-1046
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 280752
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    252 AM EST Tue Dec 28 2021

    Day 1
    Valid 12Z Tue Dec 28 2021 - 12Z Wed Dec 29 2021

    ...A MARGINAL RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF
    THE MIDWEST AND SOUTHWEST PA/NORTHERN WV...

    ...Mid-Mississippi/Ohio Valleys into Southwest PA...
    A tightly packed deep mid to upper level southwesterly to
    northeasterly flow regime sets up a solid frontal zone across the
    area of concern between a very deep cold low in Manitoba and an
    unseasonably strong/warm sub-tropical ridge over the Bahamas
    extending into the Gulf of Mexico. A small compact shortwave will
    rounding the base of the positive trof over the Southwest into the
    Central Plains by the start of the forecast period, 28.12z,
    spurring a fast moving surface wave into the Mid-Mississippi
    Valley. Strong WAA (35-50kts at 850mb) ahead of the wave will
    allow for upglide across the boundary intersecting a modest pool
    of 250-500 J/kg of MUCAPE is supported by above normal theta-E and
    with 2-3 standard deviations of moisture available in the warm
    sector with TPW values between 1-1.25". It is the initial
    strength of the moisture flux across the boundary likely to have
    ongoing convection starting across the MOKSAROK. Deep layered
    steering flow just above the strong WAA moist convergence layer
    (~85H) is quite unidirectional through depth to support a line of
    convection and potential training environment. Hourly rates of
    1-1.5"/hr supporting 1.5-2.5" totals in less than 3hrs.

    Currently, Hi-Res CAMs are suggestive of the axis of training to
    be a county or two north and west of the more hydrologically
    sensitive swath of enhanced saturated soil conditions from the NW
    AR Ozark Plateau to Perryville, MO to between Terre
    Haute/Vincennes IND. Here, NASA LIS 0-40cm saturation ratios are
    finally starting to come down to normal but remain about 70& in MO
    and 40-60% into central IND; as AHPS 2-week anomalies are still
    200-300% of normal to 150-200%, respectively. Any deviation
    southward initially could provoke an enhanced risk, but at this
    time, guidance is solidly supported to remain north enough to
    maintain a Marginal Risk of Excessive Rainfall at this time.

    Toward the afternoon/evening hours, the triggering shortwave will
    be rapidly weakening into confluent mid-level flow and the surface
    wave will shear into the frontal boundary across the Ohio Valley,
    weakening any ongoing mid-level convection. Still, the strength
    of the flux and persistence in the vicinity of the boundary with
    this anomalous flow could maintain modest showers and totals that
    may be in reach of the lowered FFGs. This is the case across the
    Upper Wabash Basin and into the upslope region of the Allegheny
    Plateau of southwest PA, northern WV. There is likely to be a
    lull in excessive threat across E Ohio, so the question is whether
    to connect up or draw this as a separate area, and given the risk
    is driven mainly by HREF probability of 1"/6hr up to 20-30%
    intersecting with similar FFG values (<1"/6hr) have decided to go
    with the smaller separated Marginal Risk area in southwest
    PA/northern WV.


    ...Kentucky...
    There are a few guidance members that suggest reinvigoration of
    overrunning, training convective elements across Central KY into
    the northern Cumberland Plateau, mainly the ARWs and the ECMWF.=20
    MUCAPEs of 150-300 J/kg are forecast and moisture/flux remains
    highly anomalous, but rain rates are not expected to be over 1"
    and the area has been recently well below average per AHPS and
    0-40cm soil saturation show 10-20% normal values, so believe
    flooding threat will be below 5% coverage and so is not depicted
    in a categorized area at this time.


    ...Central Gulf through Southern Appalachians/southern Cumberland
    Plateau...
    The aforementioned compact mid-level shortwave approach is suffice
    to break down ridging across the Gulf, allowing for sfc-85H bubble
    of increased moisture and instability to stream northward along
    the confluent northwesterly edge of the slowly retreating ridge.=20
    Increasing instability at the Gulf/LA coast with values of
    1000-1500 J/kg and confluent streamer bands may be sufficient to
    support some shallow inconsistent thunderstorm development
    throughout the morning and have some potential for training from
    the Central Gulf Coast. As the day progresses this sub-tropical
    shortwave/slug of moisture will stream north-northeast to
    northeast into the southern Appalachians/Cumberland Plateau of
    AL/TN/NW GA, enhancing TPW values to 1.5-1.7" and MUCAPE up to
    1000 J/kg after 00z. Tightening low level confluent flow may
    producing increased convergence for enhanced thunderstorms with
    potential of 1.5-1.75"/hr rates. However, there is very high
    inconsistency in placement east to west and strength of the
    convergence within the guidance suite. The 00z HRRR was most
    aggressive, further east with training across the Southern
    Appalachians in SE TN/N GA to support a Marginal Risk; though ARW
    solutions are delayed, later into the Day 2 period or further west
    as suggested by the NAM-Conest/FV3CAM. Higher FFG, dry ground
    conditions further support not delineating a categorized risk area
    at this time, though it will be going into the Day 2 period (after 29.12z).=20=20=20

    Gallina


    Day 2

    The Day 2 outlook will be updated by 0830Z.


    Day 3

    The Day 3 outlook will be updated by 0830Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!p1qWBcy-TxXVQRZsJvT3SbSxWmU2Sb006eDjOMitFug-= KIF-Ukgx9d_1GwnkXgmUIghnLWOV$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!p1qWBcy-TxXVQRZsJvT3SbSxWmU2Sb006eDjOMitFug-= KIF-Ukgx9d_1GwnkXgmUIjswOPcG$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!p1qWBcy-TxXVQRZsJvT3SbSxWmU2Sb006eDjOMitFug-= KIF-Ukgx9d_1GwnkXgmUIn-8D66W$=20


    $$




    ------------=_1640677985-57364-1046
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1640677985-57364-1046--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Dec 28 07:53:29 2021
    This is a multi-part message in MIME format...

    ------------=_1640678015-57364-1047
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 280753
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    252 AM EST Tue Dec 28 2021

    Day 1
    Valid 12Z Tue Dec 28 2021 - 12Z Wed Dec 29 2021

    ...A MARGINAL RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF
    THE MIDWEST AND SOUTHWEST PA/NORTHERN WV...

    ...Mid-Mississippi/Ohio Valleys into Southwest PA...
    A tightly packed deep mid to upper level southwesterly to
    northeasterly flow regime sets up a solid frontal zone across the
    area of concern between a very deep cold low in Manitoba and an
    unseasonably strong/warm sub-tropical ridge over the Bahamas
    extending into the Gulf of Mexico. A small compact shortwave will
    rounding the base of the positive trof over the Southwest into the
    Central Plains by the start of the forecast period, 28.12z,
    spurring a fast moving surface wave into the Mid-Mississippi
    Valley. Strong WAA (35-50kts at 850mb) ahead of the wave will
    allow for upglide across the boundary intersecting a modest pool
    of 250-500 J/kg of MUCAPE is supported by above normal theta-E and
    with 2-3 standard deviations of moisture available in the warm
    sector with TPW values between 1-1.25". It is the initial
    strength of the moisture flux across the boundary likely to have
    ongoing convection starting across the MOKSAROK. Deep layered
    steering flow just above the strong WAA moist convergence layer
    (~85H) is quite unidirectional through depth to support a line of
    convection and potential training environment. Hourly rates of
    1-1.5"/hr supporting 1.5-2.5" totals in less than 3hrs.

    Currently, Hi-Res CAMs are suggestive of the axis of training to
    be a county or two north and west of the more hydrologically
    sensitive swath of enhanced saturated soil conditions from the NW
    AR Ozark Plateau to Perryville, MO to between Terre
    Haute/Vincennes IND. Here, NASA LIS 0-40cm saturation ratios are
    finally starting to come down to normal but remain about 70& in MO
    and 40-60% into central IND; as AHPS 2-week anomalies are still
    200-300% of normal to 150-200%, respectively. Any deviation
    southward initially could provoke an enhanced risk, but at this
    time, guidance is solidly supported to remain north enough to
    maintain a Marginal Risk of Excessive Rainfall at this time.

    Toward the afternoon/evening hours, the triggering shortwave will
    be rapidly weakening into confluent mid-level flow and the surface
    wave will shear into the frontal boundary across the Ohio Valley,
    weakening any ongoing mid-level convection. Still, the strength
    of the flux and persistence in the vicinity of the boundary with
    this anomalous flow could maintain modest showers and totals that
    may be in reach of the lowered FFGs. This is the case across the
    Upper Wabash Basin and into the upslope region of the Allegheny
    Plateau of southwest PA, northern WV. There is likely to be a
    lull in excessive threat across E Ohio, so the question is whether
    to connect up or draw this as a separate area, and given the risk
    is driven mainly by HREF probability of 1"/6hr up to 20-30%
    intersecting with similar FFG values (<1"/6hr) have decided to go
    with the smaller separated Marginal Risk area in southwest
    PA/northern WV.


    ...Kentucky...
    There are a few guidance members that suggest reinvigoration of
    overrunning, training convective elements across Central KY into
    the northern Cumberland Plateau, mainly the ARWs and the ECMWF.=20
    MUCAPEs of 150-300 J/kg are forecast and moisture/flux remains
    highly anomalous, but rain rates are not expected to be over 1"
    and the area has been recently well below average per AHPS and
    0-40cm soil saturation show 10-20% normal values, so believe
    flooding threat will be below 5% coverage and so is not depicted
    in a categorized area at this time.


    ...Central Gulf through Southern Appalachians/southern Cumberland
    Plateau...
    The aforementioned compact mid-level shortwave approach is suffice
    to break down ridging across the Gulf, allowing for sfc-85H bubble
    of increased moisture and instability to stream northward along
    the confluent northwesterly edge of the slowly retreating ridge.=20
    Increasing instability at the Gulf/LA coast with values of
    1000-1500 J/kg and confluent streamer bands may be sufficient to
    support some shallow inconsistent thunderstorm development
    throughout the morning and have some potential for training from
    the Central Gulf Coast. As the day progresses this sub-tropical
    shortwave/slug of moisture will stream north-northeast to
    northeast into the southern Appalachians/Cumberland Plateau of
    AL/TN/NW GA, enhancing TPW values to 1.5-1.7" and MUCAPE up to
    1000 J/kg after 00z. Tightening low level confluent flow may
    producing increased convergence for enhanced thunderstorms with
    potential of 1.5-1.75"/hr rates. However, there is very high
    inconsistency in placement east to west and strength of the
    convergence within the guidance suite. The 00z HRRR was most
    aggressive, further east with training across the Southern
    Appalachians in SE TN/N GA to support a Marginal Risk; though ARW
    solutions are delayed, later into the Day 2 period or further west
    as suggested by the NAM-Conest/FV3CAM. Higher FFG, dry ground
    conditions further support not delineating a categorized risk area
    at this time, though it will be going into the Day 2 period (after 29.12z).=20=20=20

    Gallina


    Day 2
    Valid 12Z Tue Dec 28 2021 - 12Z Wed Dec 29 2021

    ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
    TENNESSEE VALLEY/SOUTHERN APPALACHIANS AND SOUTHERN CALIFORNIA...

    ...Tennessee Valley to Central Appalachians...
    At the start of the forecast period, 29.12z, the initial shortwave
    has sheared into the confluent southwesterly flow across the
    eastern Great Lakes leaving a quasi-stationary front across the
    Central Appalachians and Kentucky with inflection toward the Ozark
    Plateau, at the intersection of the warm, moist airmass emanating
    from the Gulf of Mexico. Ongoing convective cells Meanwhile, the
    next shortwave to round the base of the large scale trof across
    the West, will once again strengthen southwesterly flow helping to
    draw mid-level subtropical Pacific moisture across the lower MS
    valley, adding to the low-level returning Gulf Moisture. TPWs
    will be increased to 1.5-1.7" across the Delta region while and
    instability will be steadily increasing with CAPEs to 1500 J/kg
    into central MS, while a more modest but sufficient 500-750 J/kg
    should reach into the Tennessee Valley, where the returning warm
    front will help to trigger moisture convergence and deeper
    thunderstorm development. While there is a good probability for
    stronger severe rotating storms southward into MS/AL, enhancing
    mesoscale moisture flux for increased rainfall efficiency; it is
    along the warm front where multiple cells have the potential to
    train given the length of moisture flux convergence downstream and
    parallel to the boundary. Rates of 1.5" are possible and given
    training 6hr probabilities of exceeding 3" are as high as 35%
    across central TN by 00z. While instability will reduce and
    likewise with the rainfall intensity. increased deep-layer
    confluence further east across the Cumberland Plateau should help
    to expand the complex to produce broad 2-3" totals and potential
    in short duration as depicted by the NAM-Nest, GFS/NAM, ECMWF,
    ICON and Gem-Regional. As such, the potential for flash flooding
    is about the same as the FFG values reduce to the east with lower
    threshold of 1-1.5"/hr & 1.5-2"/3hrs across the Plateau into the
    Central Appalachian Mountains producing possibility of exceedance.
    As such, a Slight Risk of Excessive Rainfall has been added from
    the NE corner of MS across TN/N AL into far SE KY. A Marginal Risk
    extends southward across central MS, AL into GA where some of the
    stronger cells could produce isolated rain-rates capable of
    short-term FFG exceedance.


    ...Southern California...
    An upper-level shortwave will be starting to amplify along the
    southwester portion of the larger scale synoptic trof dominating
    Canada into the Northern Rockies. A wave further north in the
    stream will undercut across the Northern Rockies and allow for the
    shortwave to buckle further as it reaches the California Bight
    about 30.06z. As is typical with waves at the periphery of strong
    northern stream flow, there remains significant timing differences
    in the guidance resulting in large but reducing spread west to
    east, but the depth in latitude seems to be coming to strong
    agreement. It is the placement of the wave as it closes off
    across the Catalina Islands that will allow for the surface flow
    to back, tighten low level moisture gradients with solid speed and
    directional divergence aloft, weak CAA will also steepen lapse
    rates for 100-200 J/kg even onshore across Los Angeles and Orange
    counties for some shallow convective cells to develop. SoCal's
    proximity to the mean mid-level 5H pinching point will also
    support weakened cell motions to allow for cells to propagate
    along self-generated cold pools and hang up along/near terrain
    while maintaining favorable moisture flux. With the positives of
    the dynamics, the limiting factor will be the moisture which is
    likely to be limited to .75 to 1" limiting rainfall efficiency and
    overall totals. However, recent well above normal rainfall across
    the region (500-600% of normal per AHPS 7-day anomalies), deep
    soil saturation to 80-90% per NASA SPoRT LIS 0-40 ratios along
    with urban environment suggests rates of .5-1"/hr and localized
    totals up to 2" across the valley floor may contribute to flash
    flooding.=20

    Low-level flow is likely to be 20-30kts into the transverse range,
    veering toward the Peninsular range toward the end of the forecast
    period. Freezing levels may start low AoA 5000ft but should
    slowly increasing with the WAA, perhaps allowing for all rain
    across the southern most peaks in San Diego county. It is within
    orographic ascent regions that will provide longer
    duration/moderate rainfall adding to the saturated areas as well
    with an additional 2-4". As such, a Slight Risk of Excessive
    Rainfall was introduced to greatest model placement agreement
    though may need to be expanded south and eastward given timing
    trends.

    Gallina

    Day 3

    The Day 3 outlook will be updated by 0830Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!rMr1mb8GdZGoLIvrfMsaDVTWZPJtBnItF4ykZ-J8llH8= VLDi_BRgIBcJLpOIzcroMD_Sv__v$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!rMr1mb8GdZGoLIvrfMsaDVTWZPJtBnItF4ykZ-J8llH8= VLDi_BRgIBcJLpOIzcroMHn4XcYF$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!rMr1mb8GdZGoLIvrfMsaDVTWZPJtBnItF4ykZ-J8llH8= VLDi_BRgIBcJLpOIzcroMCakHt6y$=20


    $$




    ------------=_1640678015-57364-1047
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1640678015-57364-1047--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Dec 28 07:54:00 2021
    This is a multi-part message in MIME format...

    ------------=_1640678046-57364-1048
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 280753
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    253 AM EST Tue Dec 28 2021

    Day 1
    Valid 12Z Tue Dec 28 2021 - 12Z Wed Dec 29 2021

    ...A MARGINAL RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF
    THE MIDWEST AND SOUTHWEST PA/NORTHERN WV...

    ...Mid-Mississippi/Ohio Valleys into Southwest PA...
    A tightly packed deep mid to upper level southwesterly to
    northeasterly flow regime sets up a solid frontal zone across the
    area of concern between a very deep cold low in Manitoba and an
    unseasonably strong/warm sub-tropical ridge over the Bahamas
    extending into the Gulf of Mexico. A small compact shortwave will
    rounding the base of the positive trof over the Southwest into the
    Central Plains by the start of the forecast period, 28.12z,
    spurring a fast moving surface wave into the Mid-Mississippi
    Valley. Strong WAA (35-50kts at 850mb) ahead of the wave will
    allow for upglide across the boundary intersecting a modest pool
    of 250-500 J/kg of MUCAPE is supported by above normal theta-E and
    with 2-3 standard deviations of moisture available in the warm
    sector with TPW values between 1-1.25". It is the initial
    strength of the moisture flux across the boundary likely to have
    ongoing convection starting across the MOKSAROK. Deep layered
    steering flow just above the strong WAA moist convergence layer
    (~85H) is quite unidirectional through depth to support a line of
    convection and potential training environment. Hourly rates of
    1-1.5"/hr supporting 1.5-2.5" totals in less than 3hrs.

    Currently, Hi-Res CAMs are suggestive of the axis of training to
    be a county or two north and west of the more hydrologically
    sensitive swath of enhanced saturated soil conditions from the NW
    AR Ozark Plateau to Perryville, MO to between Terre
    Haute/Vincennes IND. Here, NASA LIS 0-40cm saturation ratios are
    finally starting to come down to normal but remain about 70& in MO
    and 40-60% into central IND; as AHPS 2-week anomalies are still
    200-300% of normal to 150-200%, respectively. Any deviation
    southward initially could provoke an enhanced risk, but at this
    time, guidance is solidly supported to remain north enough to
    maintain a Marginal Risk of Excessive Rainfall at this time.

    Toward the afternoon/evening hours, the triggering shortwave will
    be rapidly weakening into confluent mid-level flow and the surface
    wave will shear into the frontal boundary across the Ohio Valley,
    weakening any ongoing mid-level convection. Still, the strength
    of the flux and persistence in the vicinity of the boundary with
    this anomalous flow could maintain modest showers and totals that
    may be in reach of the lowered FFGs. This is the case across the
    Upper Wabash Basin and into the upslope region of the Allegheny
    Plateau of southwest PA, northern WV. There is likely to be a
    lull in excessive threat across E Ohio, so the question is whether
    to connect up or draw this as a separate area, and given the risk
    is driven mainly by HREF probability of 1"/6hr up to 20-30%
    intersecting with similar FFG values (<1"/6hr) have decided to go
    with the smaller separated Marginal Risk area in southwest
    PA/northern WV.


    ...Kentucky...
    There are a few guidance members that suggest reinvigoration of
    overrunning, training convective elements across Central KY into
    the northern Cumberland Plateau, mainly the ARWs and the ECMWF.=20
    MUCAPEs of 150-300 J/kg are forecast and moisture/flux remains
    highly anomalous, but rain rates are not expected to be over 1"
    and the area has been recently well below average per AHPS and
    0-40cm soil saturation show 10-20% normal values, so believe
    flooding threat will be below 5% coverage and so is not depicted
    in a categorized area at this time.


    ...Central Gulf through Southern Appalachians/southern Cumberland
    Plateau...
    The aforementioned compact mid-level shortwave approach is suffice
    to break down ridging across the Gulf, allowing for sfc-85H bubble
    of increased moisture and instability to stream northward along
    the confluent northwesterly edge of the slowly retreating ridge.=20
    Increasing instability at the Gulf/LA coast with values of
    1000-1500 J/kg and confluent streamer bands may be sufficient to
    support some shallow inconsistent thunderstorm development
    throughout the morning and have some potential for training from
    the Central Gulf Coast. As the day progresses this sub-tropical
    shortwave/slug of moisture will stream north-northeast to
    northeast into the southern Appalachians/Cumberland Plateau of
    AL/TN/NW GA, enhancing TPW values to 1.5-1.7" and MUCAPE up to
    1000 J/kg after 00z. Tightening low level confluent flow may
    producing increased convergence for enhanced thunderstorms with
    potential of 1.5-1.75"/hr rates. However, there is very high
    inconsistency in placement east to west and strength of the
    convergence within the guidance suite. The 00z HRRR was most
    aggressive, further east with training across the Southern
    Appalachians in SE TN/N GA to support a Marginal Risk; though ARW
    solutions are delayed, later into the Day 2 period or further west
    as suggested by the NAM-Conest/FV3CAM. Higher FFG, dry ground
    conditions further support not delineating a categorized risk area
    at this time, though it will be going into the Day 2 period (after 29.12z).=20=20=20

    Gallina


    Day 2
    Valid 12Z Wed Dec 29 2021 - 12Z Thu Dec 30 2021

    ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
    TENNESSEE VALLEY/SOUTHERN APPALACHIANS AND SOUTHERN CALIFORNIA...

    ...Tennessee Valley to Central Appalachians...
    At the start of the forecast period, 29.12z, the initial shortwave
    has sheared into the confluent southwesterly flow across the
    eastern Great Lakes leaving a quasi-stationary front across the
    Central Appalachians and Kentucky with inflection toward the Ozark
    Plateau, at the intersection of the warm, moist airmass emanating
    from the Gulf of Mexico. Ongoing convective cells Meanwhile, the
    next shortwave to round the base of the large scale trof across
    the West, will once again strengthen southwesterly flow helping to
    draw mid-level subtropical Pacific moisture across the lower MS
    valley, adding to the low-level returning Gulf Moisture. TPWs
    will be increased to 1.5-1.7" across the Delta region while and
    instability will be steadily increasing with CAPEs to 1500 J/kg
    into central MS, while a more modest but sufficient 500-750 J/kg
    should reach into the Tennessee Valley, where the returning warm
    front will help to trigger moisture convergence and deeper
    thunderstorm development. While there is a good probability for
    stronger severe rotating storms southward into MS/AL, enhancing
    mesoscale moisture flux for increased rainfall efficiency; it is
    along the warm front where multiple cells have the potential to
    train given the length of moisture flux convergence downstream and
    parallel to the boundary. Rates of 1.5" are possible and given
    training 6hr probabilities of exceeding 3" are as high as 35%
    across central TN by 00z. While instability will reduce and
    likewise with the rainfall intensity. increased deep-layer
    confluence further east across the Cumberland Plateau should help
    to expand the complex to produce broad 2-3" totals and potential
    in short duration as depicted by the NAM-Nest, GFS/NAM, ECMWF,
    ICON and Gem-Regional. As such, the potential for flash flooding
    is about the same as the FFG values reduce to the east with lower
    threshold of 1-1.5"/hr & 1.5-2"/3hrs across the Plateau into the
    Central Appalachian Mountains producing possibility of exceedance.
    As such, a Slight Risk of Excessive Rainfall has been added from
    the NE corner of MS across TN/N AL into far SE KY. A Marginal Risk
    extends southward across central MS, AL into GA where some of the
    stronger cells could produce isolated rain-rates capable of
    short-term FFG exceedance.


    ...Southern California...
    An upper-level shortwave will be starting to amplify along the
    southwester portion of the larger scale synoptic trof dominating
    Canada into the Northern Rockies. A wave further north in the
    stream will undercut across the Northern Rockies and allow for the
    shortwave to buckle further as it reaches the California Bight
    about 30.06z. As is typical with waves at the periphery of strong
    northern stream flow, there remains significant timing differences
    in the guidance resulting in large but reducing spread west to
    east, but the depth in latitude seems to be coming to strong
    agreement. It is the placement of the wave as it closes off
    across the Catalina Islands that will allow for the surface flow
    to back, tighten low level moisture gradients with solid speed and
    directional divergence aloft, weak CAA will also steepen lapse
    rates for 100-200 J/kg even onshore across Los Angeles and Orange
    counties for some shallow convective cells to develop. SoCal's
    proximity to the mean mid-level 5H pinching point will also
    support weakened cell motions to allow for cells to propagate
    along self-generated cold pools and hang up along/near terrain
    while maintaining favorable moisture flux. With the positives of
    the dynamics, the limiting factor will be the moisture which is
    likely to be limited to .75 to 1" limiting rainfall efficiency and
    overall totals. However, recent well above normal rainfall across
    the region (500-600% of normal per AHPS 7-day anomalies), deep
    soil saturation to 80-90% per NASA SPoRT LIS 0-40 ratios along
    with urban environment suggests rates of .5-1"/hr and localized
    totals up to 2" across the valley floor may contribute to flash
    flooding.=20

    Low-level flow is likely to be 20-30kts into the transverse range,
    veering toward the Peninsular range toward the end of the forecast
    period. Freezing levels may start low AoA 5000ft but should
    slowly increasing with the WAA, perhaps allowing for all rain
    across the southern most peaks in San Diego county. It is within
    orographic ascent regions that will provide longer
    duration/moderate rainfall adding to the saturated areas as well
    with an additional 2-4". As such, a Slight Risk of Excessive
    Rainfall was introduced to greatest model placement agreement
    though may need to be expanded south and eastward given timing
    trends.

    Gallina

    Day 3
    Valid 12Z Wed Dec 29 2021 - 12Z Thu Dec 30 2021

    ...A MARGINAL RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF
    SOUTHERN CALIFORNIA...

    ...Southern California...
    By the start of the day 3 period, 30.12z, the closed low will have
    dropped fully into the California Bight while the low level flow
    will start to direct more into far southern California into the
    Peninsular Ranges. However, while improving, much like Day 2,
    there is timing spread on that frontal zone/moisture plume enough
    to keep a Marginal Risk of Excessive Rainfall for an additional
    1-2" perhaps higher in highest slopes of the southwest facing
    terrain from LA county southward across San Diego County. While
    becoming less likely with slightly faster trend in the 00z
    guidance, there does still remain a potential for an upgrade to a
    Slight Risk with subsequent guidance cycles; especially if trend
    shifts back toward slower solutions with Hi-Res CAMs.=20

    Gallina


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!oLLWRsiQLdmMR3ahd7DsiMtsaP7GN6ReRDvuyyiUcGcI= 5uuk2R82afWGvRENdwohJII87cE7$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!oLLWRsiQLdmMR3ahd7DsiMtsaP7GN6ReRDvuyyiUcGcI= 5uuk2R82afWGvRENdwohJP6RZe4s$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!oLLWRsiQLdmMR3ahd7DsiMtsaP7GN6ReRDvuyyiUcGcI= 5uuk2R82afWGvRENdwohJBmzvrkE$=20


    $$




    ------------=_1640678046-57364-1048
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1640678046-57364-1048--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Dec 29 07:46:45 2021
    This is a multi-part message in MIME format...

    ------------=_1640764010-74861-426
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 290746
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    245 AM EST Wed Dec 29 2021

    Day 1
    Valid 12Z Wed Dec 29 2021 - 12Z Thu Dec 30 2021

    ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
    TENNESSEE VALLEY/SOUTHERN APPALACHIANS AND SOUTHERN CALIFORNIA...

    ...Tennessee Valley to Central Appalachians...

    At the start of the day 1 period, the quasi-stationary front will
    continue to sag southward across central and eastern Kentucky and
    through the Central Appalachians. Further south, there is a good
    possibility there will be ongoing but weakening scattered
    convection along the northwest periphery of the synoptic-scale
    subtropical ridge in the Bahamas and the impinging aforementioned
    northern stream flow across the southern Cumberland Plateau,
    southern Appalachians. These cells help to demarcate a ribbon of
    enhanced sub-tropical moisture/higher theta-E air originating from
    the Western Caribbean, but solidly in place across the Lower
    Mississippi River Valley. The next in a series of shortwaves will
    be emerging into the south-central Plains and rocketing northeast
    through the strong southwest to northeast flow. This wave and
    associated buckle in the 3H jet will provide strong synoptic
    dynamics within the right entrance region to develop a new surface
    wave along the front through the Ozark Plateau into the Tri-Rivers
    confluence region and through the Ohio Valley by late day.

    Strong moisture flux in the 8-5H layer from the sub-tropic stream
    will over-top the return moisture from the Gulf and increase total
    PWAT values to 1.5-1.7" across the MS Delta Region into the
    Tennessee Valley. Combined with growing unstable environment with
    CAPEs of 1500 J/kg into central MS and 750-1000 J/kg into W TN and
    the strengthening forcing, strong thunderstorms are expected with
    high rainfall rates of 1.5-2"/hr. Strong moisture flux
    convergence along/south of the returning front across W TN/N MS
    will have increased length to support multiple cells and with deep
    layered unidirectional flow, promoting potential for training.=20
    Likely due to confluent moisture streams, Hi-Res CAMs are
    bifurcating on location of best training/convergence resulting in
    lowered HREF Probability values, but guidance does support the
    evolution with a slight southward trend, particularly in the
    global guidance members. As such, the Slight Risk has been
    expanded west and south, centering on area that received 1-2" of
    rainfall overnight early Wednesday across N AL. By late evening,
    deep layer flow will support multiple rounds across E TN, though
    likely to be weaker, in general, due to proximity from the
    instability source further upstream. Yet, confidence is higher
    across this area for the Slight Risk as HREF probabilities exceed
    70% for higher rates/3hr totals.

    South across the lower MS River Valley, individual cells may have
    a greater potential for cell rotation (see SPC D1 discussion) and
    that will support enhanced storm-scale moisture flux convergence
    to enhance moisture flux and rainfall efficiency. However, given
    orientation to the flow and potential for greater right-hand
    turning across the mean deep layer flow should be much less likely
    for training across central and southern MS and progressing into
    AL through the evening, resulting in a more scattered nature to
    flash flooding potential and as such, are encompassed in a broader
    Marginal Risk southward.


    ...Southern California...
    An upper-level shortwave will be starting to amplify along the
    central California coast throughout the day before swinging more
    positive to neutral tilt while starting to pinch off into a closed
    low by 30.12z near Point Conception. Models continue show an
    increase in spread due to timing and how strong it closes off the
    low with the NAM/UKMET a bit slower/deeper and southward relative
    the remaining suite and results in a fairly sizable timing
    difference with the approach of the cold front/moisture plume.=20=20
    Still, all solutions do depict strengthening and backing flow to
    support enhanced moisture convergence with 30-40kts of 85H flow
    directed toward both the Transverse and Peninsular Ranges with
    time. Steepening lapse rates due to the approach of the cold
    upper low aloft may further support and areal expansion of weak
    instability to 250 J/kg within moderately diffluent flow aloft
    supporting increased vertical depth to showers/thunderstorms
    resulting in enhanced rain rates of up to .5"/hr even in the lower
    elevations. Slow trending upward with moisture to 1" and IVT
    values ticking up to 400 to 500 kg/ms further provide confidence
    to heavy rainfall signatures even across areas without orographic
    enhancement with 1-2" possible.=20

    Favorably directed low to mid-level flow will support enhanced
    orographic ascent across the Transverse Range while also
    supporting WAA to raise snow levels throughout the forecast
    period. While the highest peaks of the San Gabriel and San
    Bernardino Ranges will continue to have heavy snow, mid-slope
    rainfall totals of 2-4+", perhaps over some snow melt and
    saturated soils due to 500-600% of normal rainfall over the last
    week (per AHPS), mud slide, debris flows and flash flooding are
    possible supporting the Slight Risk already in place. Hi-Res
    CAM's finer resolution helps to refine the Slight Risk area a bit
    more to expand across the Santa Monica Range, Santa Ana, Palomar
    mountains as well as mid-slopes of the San Bernadino Range. Slow
    NAM/NAM-Nest solutions while of lower probability keep the
    westward extent of the Marginal across Santa Barbara county at
    this time.=20

    Gallina


    Day 2

    The Day 2 outlook will be updated by 0830Z.


    Day 3

    The Day 3 outlook will be updated by 0830Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!qRgeyDRlHNG4s-c8azSRu9eEuQmcGZw9Xr6ZlchgucKv= p_tr_h_4bxWubOSD4UxOqm-waPmy$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!qRgeyDRlHNG4s-c8azSRu9eEuQmcGZw9Xr6ZlchgucKv= p_tr_h_4bxWubOSD4UxOql4MAcoP$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!qRgeyDRlHNG4s-c8azSRu9eEuQmcGZw9Xr6ZlchgucKv= p_tr_h_4bxWubOSD4UxOqpA8LV9_$=20


    $$




    ------------=_1640764010-74861-426
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1640764010-74861-426--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Dec 29 07:47:16 2021
    This is a multi-part message in MIME format...

    ------------=_1640764041-74861-427
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 290747
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    246 AM EST Wed Dec 29 2021

    Day 1
    Valid 12Z Wed Dec 29 2021 - 12Z Thu Dec 30 2021

    ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
    TENNESSEE VALLEY/SOUTHERN APPALACHIANS AND SOUTHERN CALIFORNIA...

    ...Tennessee Valley to Central Appalachians...

    At the start of the day 1 period, the quasi-stationary front will
    continue to sag southward across central and eastern Kentucky and
    through the Central Appalachians. Further south, there is a good
    possibility there will be ongoing but weakening scattered
    convection along the northwest periphery of the synoptic-scale
    subtropical ridge in the Bahamas and the impinging aforementioned
    northern stream flow across the southern Cumberland Plateau,
    southern Appalachians. These cells help to demarcate a ribbon of
    enhanced sub-tropical moisture/higher theta-E air originating from
    the Western Caribbean, but solidly in place across the Lower
    Mississippi River Valley. The next in a series of shortwaves will
    be emerging into the south-central Plains and rocketing northeast
    through the strong southwest to northeast flow. This wave and
    associated buckle in the 3H jet will provide strong synoptic
    dynamics within the right entrance region to develop a new surface
    wave along the front through the Ozark Plateau into the Tri-Rivers
    confluence region and through the Ohio Valley by late day.

    Strong moisture flux in the 8-5H layer from the sub-tropic stream
    will over-top the return moisture from the Gulf and increase total
    PWAT values to 1.5-1.7" across the MS Delta Region into the
    Tennessee Valley. Combined with growing unstable environment with
    CAPEs of 1500 J/kg into central MS and 750-1000 J/kg into W TN and
    the strengthening forcing, strong thunderstorms are expected with
    high rainfall rates of 1.5-2"/hr. Strong moisture flux
    convergence along/south of the returning front across W TN/N MS
    will have increased length to support multiple cells and with deep
    layered unidirectional flow, promoting potential for training.=20
    Likely due to confluent moisture streams, Hi-Res CAMs are
    bifurcating on location of best training/convergence resulting in
    lowered HREF Probability values, but guidance does support the
    evolution with a slight southward trend, particularly in the
    global guidance members. As such, the Slight Risk has been
    expanded west and south, centering on area that received 1-2" of
    rainfall overnight early Wednesday across N AL. By late evening,
    deep layer flow will support multiple rounds across E TN, though
    likely to be weaker, in general, due to proximity from the
    instability source further upstream. Yet, confidence is higher
    across this area for the Slight Risk as HREF probabilities exceed
    70% for higher rates/3hr totals.

    South across the lower MS River Valley, individual cells may have
    a greater potential for cell rotation (see SPC D1 discussion) and
    that will support enhanced storm-scale moisture flux convergence
    to enhance moisture flux and rainfall efficiency. However, given
    orientation to the flow and potential for greater right-hand
    turning across the mean deep layer flow should be much less likely
    for training across central and southern MS and progressing into
    AL through the evening, resulting in a more scattered nature to
    flash flooding potential and as such, are encompassed in a broader
    Marginal Risk southward.


    ...Southern California...
    An upper-level shortwave will be starting to amplify along the
    central California coast throughout the day before swinging more
    positive to neutral tilt while starting to pinch off into a closed
    low by 30.12z near Point Conception. Models continue show an
    increase in spread due to timing and how strong it closes off the
    low with the NAM/UKMET a bit slower/deeper and southward relative
    the remaining suite and results in a fairly sizable timing
    difference with the approach of the cold front/moisture plume.=20=20
    Still, all solutions do depict strengthening and backing flow to
    support enhanced moisture convergence with 30-40kts of 85H flow
    directed toward both the Transverse and Peninsular Ranges with
    time. Steepening lapse rates due to the approach of the cold
    upper low aloft may further support and areal expansion of weak
    instability to 250 J/kg within moderately diffluent flow aloft
    supporting increased vertical depth to showers/thunderstorms
    resulting in enhanced rain rates of up to .5"/hr even in the lower
    elevations. Slow trending upward with moisture to 1" and IVT
    values ticking up to 400 to 500 kg/ms further provide confidence
    to heavy rainfall signatures even across areas without orographic
    enhancement with 1-2" possible.=20

    Favorably directed low to mid-level flow will support enhanced
    orographic ascent across the Transverse Range while also
    supporting WAA to raise snow levels throughout the forecast
    period. While the highest peaks of the San Gabriel and San
    Bernardino Ranges will continue to have heavy snow, mid-slope
    rainfall totals of 2-4+", perhaps over some snow melt and
    saturated soils due to 500-600% of normal rainfall over the last
    week (per AHPS), mud slide, debris flows and flash flooding are
    possible supporting the Slight Risk already in place. Hi-Res
    CAM's finer resolution helps to refine the Slight Risk area a bit
    more to expand across the Santa Monica Range, Santa Ana, Palomar
    mountains as well as mid-slopes of the San Bernadino Range. Slow
    NAM/NAM-Nest solutions while of lower probability keep the
    westward extent of the Marginal across Santa Barbara county at
    this time.=20

    Gallina


    Day 2
    Valid 12Z Wed Dec 29 2021 - 12Z Thu Dec 30 2021

    ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF
    SOUTHERN CALIFORNIA...

    ...Southern California...
    By the start of the day 2 period, 30/12z, the shortwave will have
    become closed off entering the California Bight. The associated
    surface low will move south-southeast through the Channel Islands
    and with the 85H low still in proximity, low-level flow and
    moisture transport will continue to be directed into southern
    California into Day 2. The Hi-Res CAMs along with NAM/NAM-Nest
    solutions continue to remain relatively slow mainly due to
    stronger that average closed low solutions that delay eastward
    progression of the moisture feed/transport. Large scale pattern
    suggests next kicker wave upstream is likely to keep the shortwave
    progressive and kicking through northern Baja California by early
    Friday and the NAM/UKMET are just outlier solutions to this
    evolution for overall preference.

    With that stated, overall stronger surface wave and therefore
    moisture flux transport within the 1" Total PWat narrow plume has
    trended slower and allows for longer duration even flow that may
    parallel the Peninsular Ranges into the eastern San Bernardino
    Range. ARW/ARW2/HRRR and therefore HREF solutions (paired back to
    account for out of place NAM-NEST), support an additional 2-4"
    across south and southwest facing topography east of LA county,
    with 1-3" from GFS/ECMWF and CMC (including Gem-Regional). With
    potential of .33-.5"/hr rates and these totals over saturated
    grounds 0-40cm soil ratios between 70-80% per NASA SPoRT and rain
    from the day 1 period, supports an upgrade to Slight Risk where
    all these elements overlap within the bulk of the guidance suite.=20
    The surrounding Marginal Risk extends to the Mexican border, to
    account for the potential of some further slowing down of
    solutions, have pulled the Marginal Risk back to the Santa Monica
    Range and through much of LA county foothills.

    Gallina

    Day 3

    The Day 3 outlook will be updated by 0830Z.


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!oZ4dMH5FCE4f_m_7ZHvmK0N0Xlsmvm3RmWhhZupPCZLK= iQWf8Yo764hP-al3izSoELOP2bIc$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!oZ4dMH5FCE4f_m_7ZHvmK0N0Xlsmvm3RmWhhZupPCZLK= iQWf8Yo764hP-al3izSoEIIf_brh$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!oZ4dMH5FCE4f_m_7ZHvmK0N0Xlsmvm3RmWhhZupPCZLK= iQWf8Yo764hP-al3izSoEM4ZLEQD$=20


    $$




    ------------=_1640764041-74861-427
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1640764041-74861-427--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Dec 29 07:48:16 2021
    This is a multi-part message in MIME format...

    ------------=_1640764101-74861-429
    Content-Type: text/plain
    Content-Transfer-Encoding: Quoted-printable

    FOUS30 KWBC 290748
    QPFERD
    Excessive Rainfall Discussion
    NWS Weather Prediction Center College Park MD
    247 AM EST Wed Dec 29 2021

    Day 1
    Valid 12Z Wed Dec 29 2021 - 12Z Thu Dec 30 2021

    ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
    TENNESSEE VALLEY/SOUTHERN APPALACHIANS AND SOUTHERN CALIFORNIA...

    ...Tennessee Valley to Central Appalachians...

    At the start of the day 1 period, the quasi-stationary front will
    continue to sag southward across central and eastern Kentucky and
    through the Central Appalachians. Further south, there is a good
    possibility there will be ongoing but weakening scattered
    convection along the northwest periphery of the synoptic-scale
    subtropical ridge in the Bahamas and the impinging aforementioned
    northern stream flow across the southern Cumberland Plateau,
    southern Appalachians. These cells help to demarcate a ribbon of
    enhanced sub-tropical moisture/higher theta-E air originating from
    the Western Caribbean, but solidly in place across the Lower
    Mississippi River Valley. The next in a series of shortwaves will
    be emerging into the south-central Plains and rocketing northeast
    through the strong southwest to northeast flow. This wave and
    associated buckle in the 3H jet will provide strong synoptic
    dynamics within the right entrance region to develop a new surface
    wave along the front through the Ozark Plateau into the Tri-Rivers
    confluence region and through the Ohio Valley by late day.

    Strong moisture flux in the 8-5H layer from the sub-tropic stream
    will over-top the return moisture from the Gulf and increase total
    PWAT values to 1.5-1.7" across the MS Delta Region into the
    Tennessee Valley. Combined with growing unstable environment with
    CAPEs of 1500 J/kg into central MS and 750-1000 J/kg into W TN and
    the strengthening forcing, strong thunderstorms are expected with
    high rainfall rates of 1.5-2"/hr. Strong moisture flux
    convergence along/south of the returning front across W TN/N MS
    will have increased length to support multiple cells and with deep
    layered unidirectional flow, promoting potential for training.=20
    Likely due to confluent moisture streams, Hi-Res CAMs are
    bifurcating on location of best training/convergence resulting in
    lowered HREF Probability values, but guidance does support the
    evolution with a slight southward trend, particularly in the
    global guidance members. As such, the Slight Risk has been
    expanded west and south, centering on area that received 1-2" of
    rainfall overnight early Wednesday across N AL. By late evening,
    deep layer flow will support multiple rounds across E TN, though
    likely to be weaker, in general, due to proximity from the
    instability source further upstream. Yet, confidence is higher
    across this area for the Slight Risk as HREF probabilities exceed
    70% for higher rates/3hr totals.

    South across the lower MS River Valley, individual cells may have
    a greater potential for cell rotation (see SPC D1 discussion) and
    that will support enhanced storm-scale moisture flux convergence
    to enhance moisture flux and rainfall efficiency. However, given
    orientation to the flow and potential for greater right-hand
    turning across the mean deep layer flow should be much less likely
    for training across central and southern MS and progressing into
    AL through the evening, resulting in a more scattered nature to
    flash flooding potential and as such, are encompassed in a broader
    Marginal Risk southward.


    ...Southern California...
    An upper-level shortwave will be starting to amplify along the
    central California coast throughout the day before swinging more
    positive to neutral tilt while starting to pinch off into a closed
    low by 30.12z near Point Conception. Models continue show an
    increase in spread due to timing and how strong it closes off the
    low with the NAM/UKMET a bit slower/deeper and southward relative
    the remaining suite and results in a fairly sizable timing
    difference with the approach of the cold front/moisture plume.=20=20
    Still, all solutions do depict strengthening and backing flow to
    support enhanced moisture convergence with 30-40kts of 85H flow
    directed toward both the Transverse and Peninsular Ranges with
    time. Steepening lapse rates due to the approach of the cold
    upper low aloft may further support and areal expansion of weak
    instability to 250 J/kg within moderately diffluent flow aloft
    supporting increased vertical depth to showers/thunderstorms
    resulting in enhanced rain rates of up to .5"/hr even in the lower
    elevations. Slow trending upward with moisture to 1" and IVT
    values ticking up to 400 to 500 kg/ms further provide confidence
    to heavy rainfall signatures even across areas without orographic
    enhancement with 1-2" possible.=20

    Favorably directed low to mid-level flow will support enhanced
    orographic ascent across the Transverse Range while also
    supporting WAA to raise snow levels throughout the forecast
    period. While the highest peaks of the San Gabriel and San
    Bernardino Ranges will continue to have heavy snow, mid-slope
    rainfall totals of 2-4+", perhaps over some snow melt and
    saturated soils due to 500-600% of normal rainfall over the last
    week (per AHPS), mud slide, debris flows and flash flooding are
    possible supporting the Slight Risk already in place. Hi-Res
    CAM's finer resolution helps to refine the Slight Risk area a bit
    more to expand across the Santa Monica Range, Santa Ana, Palomar
    mountains as well as mid-slopes of the San Bernadino Range. Slow
    NAM/NAM-Nest solutions while of lower probability keep the
    westward extent of the Marginal across Santa Barbara county at
    this time.=20

    Gallina


    Day 2
    Valid 12Z Thu Dec 30 2021 - 12Z Fri Dec 31 2021

    ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF
    SOUTHERN CALIFORNIA...

    ...Southern California...
    By the start of the day 2 period, 30/12z, the shortwave will have
    become closed off entering the California Bight. The associated
    surface low will move south-southeast through the Channel Islands
    and with the 85H low still in proximity, low-level flow and
    moisture transport will continue to be directed into southern
    California into Day 2. The Hi-Res CAMs along with NAM/NAM-Nest
    solutions continue to remain relatively slow mainly due to
    stronger that average closed low solutions that delay eastward
    progression of the moisture feed/transport. Large scale pattern
    suggests next kicker wave upstream is likely to keep the shortwave
    progressive and kicking through northern Baja California by early
    Friday and the NAM/UKMET are just outlier solutions to this
    evolution for overall preference.

    With that stated, overall stronger surface wave and therefore
    moisture flux transport within the 1" Total PWat narrow plume has
    trended slower and allows for longer duration even flow that may
    parallel the Peninsular Ranges into the eastern San Bernardino
    Range. ARW/ARW2/HRRR and therefore HREF solutions (paired back to
    account for out of place NAM-NEST), support an additional 2-4"
    across south and southwest facing topography east of LA county,
    with 1-3" from GFS/ECMWF and CMC (including Gem-Regional). With
    potential of .33-.5"/hr rates and these totals over saturated
    grounds 0-40cm soil ratios between 70-80% per NASA SPoRT and rain
    from the day 1 period, supports an upgrade to Slight Risk where
    all these elements overlap within the bulk of the guidance suite.=20
    The surrounding Marginal Risk extends to the Mexican border, to
    account for the potential of some further slowing down of
    solutions, have pulled the Marginal Risk back to the Santa Monica
    Range and through much of LA county foothills.

    Gallina

    Day 3
    Valid 12Z Thu Dec 30 2021 - 12Z Fri Dec 31 2021

    ...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF
    CENTRAL ARKANSAS THROUGH THE LOWER TENNESSEE VALLEY...

    ...Lower Mississippi into Lower Ohio/Tennessee River Valleys...
    The next in a series of shortwave emerging out of the Southwest
    into strong/tightly packed southwest to northeast flow exits into
    the Southern Plains very late Friday into early Saturday morning.=20
    Unlike the prior waves, it was a bit deeper and closed off
    southwest of the southern California coast at the base of the
    dominating global scale trof over the Canadian Rockies into the
    south. As is typical of this setup, there has been, and continues
    to be sizable model variation in resolving critical details, such
    as cyclone intensity and depth in latitude. The NAM/UKMET
    deepened the wave further west and significantly retarded its
    ejection relative to the GFS/ECMWF/CMC and ensemble suite. The
    overall pattern and strength of upstream jet axis/kicker shortwave
    would suggest the latter is more probable and so has become WPC's preference.=20

    Much like prior two systems, the wave will induce another but
    slightly stronger surface and low-level response with strong WAA
    and moisture flux transport off an open Gulf of Mexico.=20
    Internally to this broad Gulf moisture, is a further connection of
    higher theta-E air out of the Western Caribbean through the
    Yucatan Channel into the Lower Mississippi River Valley. Mid to
    upper-level contribution of above normal moisture out continues to
    stream out of the sub-tropical Pacific across Texas, resulting in
    3 standard deviation of moisture (~1.75" TPW) being advected
    through strong WAA response to the approaching by late evening on
    Friday into early morning Saturday. The warm front will surge
    north across the Mississippi River into the Lower Tennessee Valley
    and with strong veered low-level flow and 50-60kts of 85H LLJ,
    strong moisture flux convergence along the frontal zone. Deep
    layer unidirectional flow will once again support a training
    environment at/along the boundary to support a solid potential for
    localized heavy rainfall and flash flooding.=20

    A Slight Risk of Excessive Rainfall has been placed from Central
    Arkansas across W KY/TN. The remaining preferred guidance suggest
    a narrower swath of 2"/hr rates and totals 2-4" totals by 01.12z
    with isolated 5" values even at this range. While there is pretty
    strong agreement in the width of the rainfall footprint, there
    remains a 100-150 mile difference northwest to southeast from the
    ECMWF to the northwest to a tighter clustering southwest.=20
    Preference was given to the tighter clustering/GFS/WPC
    Bias-corrected Ensemble but the Slight Risk was broadened at this
    time to account for such a spread, as well as trying to account
    for swath of worsened ground conditions due to recent rainfall.=20
    ECMWF solution would align fairly well to the AHPS 14-day 150-300%
    anomaly, while the other solutions would overlap expected forecast
    areas from the day 1 period across W TN. So with all this
    accounted for, there remains some potential for an upgrade to a
    Moderate Risk as the spread reduces and antecedent ground
    conditions are accounted for in subsequent issuances. A broad
    marginal encompasses the Slight, accounting for downstream
    uncertainty into the Ohio Valley or across to the southern
    Cumberland Plateau.


    ...Mid to Lower Slopes of Mogollon Rim of Central Arizona into
    Extreme western New Mexico...
    Closed low in the base of the larger synoptic trof will already be
    progressing along the Arizona/Old Mexico border. Global guidance
    denotes plenty of uncertainty in timing due to large differences
    in evolution/strength of the closed low through the California
    Bight. The NAM/UKMET are notably slower than the GFS/ECMWF/CMC.=20
    WPC along with ensemble suite are favoring the more progressive
    nature given the upstream evolution across the northern portion of
    the trough, so there is some increased confidence. Remaining low
    to mid-level moisture transported into the lower Colorado Valley
    in the day 2 period will be experiencing veering flow to more
    southwest and westerly in the lowest levels, so favorably oriented
    to the central Mogollon Rim to eastern extents. Total PWat values
    of 1" will be reducing but moisture flux is about 2-2.5 standard
    deviations over the mean and IVT values will still be in the
    200-400 kg/ms range which is about 1 to 3 standard anomalies over
    the 30 year running mean. Up to 1.25" was expected before 31.12z
    with an additional 1-2" through the early morning period.

    In combination with recent 7-day rainfall anomaly about 300-600%
    of normal across central Arizona and north (100-300% south) deep
    soil saturation ratios are 70-80%, so 1-3" of additional rain
    particularly in complex terrain pose a low-end risk of increased
    runoff and flooding. Rain rates are likely to be .25-.33"/hr, so
    flash flooding is not particularly probable, but will continue
    monitor trend, particularly into Hi-RES window. As such, a
    Marginal Risk of Excessive Rainfall was added for areas of the low
    to mid-Rim below freezing levels where heavy snow is expected
    above and onto the Plateau.=20=20=20=20

    Gallina


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!uvqngbBn-taWOz311rLqHZmh2m4phwrqkRQZpAJ52tAw= kbruyUEw8u5xWLGS0Rt1zYO0wpiU$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!uvqngbBn-taWOz311rLqHZmh2m4phwrqkRQZpAJ52tAw= kbruyUEw8u5xWLGS0Rt1zevlee84$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!uvqngbBn-taWOz311rLqHZmh2m4phwrqkRQZpAJ52tAw= kbruyUEw8u5xWLGS0Rt1zWU4QDK-$=20


    $$




    ------------=_1640764101-74861-429
    Content-Type: text/plain; charset="US-ASCII"
    Content-Disposition: inline
    Content-Transfer-Encoding: 7BIT

    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. ------------=_1640764101-74861-429--

    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)