This is a multi-part message in MIME format...

------------=_1640719168-57364-1267
Content-Type: text/plain
Content-Transfer-Encoding: Quoted-printable

ACUS11 KWNS 281919
SWOMCD
SPC MCD 281918=20
MSZ000-LAZ000-282145-

Mesoscale Discussion 2068
NWS Storm Prediction Center Norman OK
0118 PM CST Tue Dec 28 2021

Areas affected...portions of eastern Louisiana into southern
Mississippi

Concerning...Severe potential...Watch unlikely=20

Valid 281918Z - 282145Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated severe threat may develop in the next couple
of hours across portions of eastern Louisiana into southern
Mississippi. The strongest, longest lasting storms may produce a
couple of damaging wind gusts/marginally severe hail stones or a
brief tornado. A WW issuance is not currently expected given the
sparse nature of the severe threat.

DISCUSSION...Warm-air advection continues to transport moisture
north from the Gulf of Mexico into the TN Valley in advance of a 999
mb surface low along the KS/MO border. This moist low-level airmass
remains modestly capped, though continued warming and moistening
beneath the inversion layer has been gradually eroding the cap
across eastern LA into southern MS per 18Z mesoanalysis. In
addition, visible satellite depicts a gravity wave propagating
across central MS/LA, which may act as an additional source of lift.
Finally, both 12Z NAM and 19Z RAP forecast soundings show cooling of
the inversion layer in the 20-22Z time frame. As such, convective
initiation appears likely within the next couple of hours despite
overall weak synoptic forcing for ascent.

925-850 mb flow is expected to either remain modest or even weaken
further as the surface low weakens while tracking northeast.
Nonetheless, modest veering and strengthening within the lowest 3 km
supports 150-300 m2/s2 0-3km SRH per DGX/LIX VWPs sampled within the
last half hour. Given semi-discrete/discrete storms modes, 30-40 kts
of effective bulk shear, and 1000-2000 J/kg MLCAPE (driven by 7 C/km
mid-level lapse rates atop near 70 F dewpoints), transient
supercells will likely be the dominant storm mode. Any stronger,
more sustained supercell structure that can materialize may produce
damaging gusts, marginally severe hail, or perhaps a brief tornado
(as 150-200 m2/s2 SRH sampled in the VWPs resides in the 0-1 km
layer). However, given the isolated nature of the severe threat, a
WW issuance is not currently anticipated.

..Squitieri/Hart.. 12/28/2021

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!pL2B2HLy-wWmBairrgUyjIqg3pjmYF8Q62yLmFKj8AoQV4-RO65f_6RqyCKAxpaHV-ZJbpk4$=
for graphic product...

ATTN...WFO...MOB...JAN...LIX...LCH...

LAT...LON 30508956 29978990 30039043 30179116 30559186 32369058
32678976 32408875 31518910 30508956=20



------------=_1640719168-57364-1267
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. ------------=_1640719168-57364-1267--

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