SPC AC 050031
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0631 PM CST Sat Dec 04 2021
Valid 050100Z - 051200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms are possible from east Texas and southern
Oklahoma, through parts of the mid South.
...01z Update...
Weak upper vort/short-wave trough has sheared east across northern
AL and earlier convection, with isolated lightning, has mostly
dissipated. A secondary upper vort is settling east-southeast across
the Arklatex this evening and this feature remains lightning-free
with very little convection. However, a few thunderstorms have
developed, and continue, within deeper moisture axis across the
upper TX Coastal region. This activity has shown enough longevity to
suggest it may not dissipate quickly this evening. Will extend
thunder probabilities south to include more of southeast TX in
thunder.
00z sounding from SHV exhibited substantial conditional instability
this evening with steep lapse rates. While surface-based parcels are
inhibited, northern extent of this air mass will experience
increasing low-level warm advection later tonight as southern branch
of LLJ begins to strengthen across northeast TX/southeast OK into
western AR. Given the thermodynamic profile at SHV there is some
concern for robust elevated convection after midnight. At this time
it appears convection will remain somewhat isolated and vertical
shear is not forecast to be that strong. While some hail could be
noted with the strongest updrafts, will not introduce severe
probabilities across this region as hail sizes should remain mostly
below 1 inch.
..Darrow.. 12/05/2021
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