Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1158 PM CST Tue Jan 23 2024
Valid 241200Z - 251200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
LOUISIANA AND SOUTHERN MISSISSIPPI...
...SUMMARY...
Isolated to scattered severe thunderstorms may occur today from
coastal/southeast Texas into parts of the Southeast. The best chance
for a few tornadoes and damaging winds appears to be across southern
Louisiana and Mississippi.
...Coastal/Southeast Texas into the Southeast...
An upper trough over the Southwest and northern Mexico will eject
over the southern Plains today. A broad swath of 50-60 kt
southwesterly flow ahead of this feature will overspread much of
coastal/southeast TX into the lower MS Valley through the period. At
the surface, a nearly stationary front will be draped from northeast
Mexico into south TX, extending northeastward into the ArkLaTex.
This boundary should move little through the day, before eventually
advancing slowly southeastward tonight. Low-level moisture should
gradually advance northward today across the lower MS Valley and
Southeast along a diffuse warm front. This will occur in tandem with
a weak surface low and subtle southern-stream shortwave trough.
Numerous to widespread convection will likely be ongoing at the
start of the period from far southeast TX into LA along and south of
the front. This activity is expected to move east-northeastward
across the lower MS Valley today while posing some severe risk. Mid
to upper 60s surface dewpoints should be in place ahead of these
thunderstorms across southern LA/MS. While mid-level lapse rates are
expected to remain poor, modest diurnal heating should aid in the
development of at least weak instability (MLCAPE generally 500-1000
J/kg) later this morning and early afternoon.
There are still some differences in short-term model guidance
regarding the strength of a southerly low-level jet across this
region. Still, enough low-level shear is evident from various
NAM/RAP/HRRR forecast soundings to support updraft rotation. A
Slight Risk has been introduced across parts of LA into southern MS
where it appears the best chance for pre-frontal
convection/supercells and a few tornadoes will exist. Thunderstorms
may eventually consolidate into a line/cluster by this afternoon,
while posing more of a damaging wind threat as they continue
eastward. The overall severe threat should gradually diminish into
western AL where weaker instability and less low-level moisture
should be present.
Isolated thunderstorms posing a threat for hail and strong/gusty
winds also appear possible at the start of the period later this
morning across parts of south/coastal TX. This convection will
probably tend to remain elevated and eventually get undercut by the
front. Additional thunderstorms may develop this afternoon and
evening across northeast Mexico and eventually advance into south TX
as ascent associated with the upper trough overspreads this region.
Modestly steepened mid-level lapse rates and strong deep-layer shear
should aid convective organization with any thunderstorms that form.
Isolated large hail appears to be the main threat, but any
thunderstorms that can remain along the cold front could be
near-surface-based and also pose some damaging wind risk.
..Gleason/Thornton.. 01/24/2024
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