ACUS01 KWNS 281949
SWODY1
SPC AC 281947

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0147 PM CST Sat Dec 28 2024

Valid 282000Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND TONIGHT ACROSS PORTIONS OF EAST TEXAS...LOUISIANA...CENTRAL AND
SOUTHERN MISSISSIPPI...AND SOUTHWESTERN ALABAMA...

...SUMMARY...
Tornadoes (some strong with at least EF2 damage possible), severe
gusts and hail are expected today into tonight. The threat area will
continue to shift eastward across east Texas and the lower
Mississippi Valley today, then over the Tennessee Valley, parts of
Georgia, and the central Gulf Coast tonight.

...20Z Update...
Severe probabilities have been adjusted in portions of central into
East Texas as well as portions of Arkansas/western Tennessee. These
areas have been impacted by earlier convection and further
destabilization does not appear likely. The remainder of the
outlook, the Moderate risk area in particular, is unchanged. The
corridor of greatest concern appears to be from portions of central
Louisiana into southwest Mississippi. Upper 60s to low 70s dewpoints
are in place and the potential for discrete/semi-discrete storms
should be maximized here later this afternoon/evening as the
mid-level jet moves overhead and the low-level jet strengthens.

..Wendt.. 12/28/2024

.PREV DISCUSSION... /ISSUED 1029 AM CST Sat Dec 28 2024/

...East TX to AL/GA...
A powerful mid-level shortwave trough and associated 80-90 knot jet
max will rotate quickly eastward across TX today and become
negatively-tilted as it tracks into the lower MS Valley this
evening. Ample low-level moisture (dewpoints in the mid 60s to
lower 70s) is in place ahead of this system across east TX, much of
LA, and central/southern MS. Morning convection is slowly weakening
across the warm sector, and low-clouds will continue to erode. This
will help to develop a corridor of moderate instability with MLCAPE
values of 1500-2000 J/kg. This will set the stage for a significant
severe weather event through the evening as supercells and bowing
structures form over east TX and race eastward across LA into MS.

The co-location of the mid-level jet, strengthening winds in the
low-levels, surface cyclogenesis, and ample moisture provide a synoptically-evident setup for all severe hazards through the
evening. The corridor of greatest concern will be late afternoon
through the evening from central LA into central MS. Considered an
upgrade to HIGH for this area, but will maintain the ongoing MDT
after consultation with local WFOs. Strong and long-tracked
tornadoes and widespread damaging winds are possible in this region,
with the primary uncertainty regarding storm-mode and linear forcing mechanisms.

Activity will spread across AL overnight, where slightly less
low-level moisture will somewhat decrease the overall severe threat.
Nevertheless, an active squall line with damaging wind potential
and embedded rotating storms/tornado threat will likely persist.

$$
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