SPC 0830Z Day 3 Outlook

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0226 AM CST Mon Nov 23 2020

Valid 251200Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE LOWER/MID MISSISSIPPI VALLEY...TENNESSEE VALLEY...AND
SOUTHEAST...

...SUMMARY...
Isolated strong to severe thunderstorms may occur Wednesday across
parts of the lower/mid Mississippi Valley into the Tennessee Valley
and Southeast.

...Lower/Mid Mississippi Valley into the Tennessee Valley and
Southeast...
A closed upper low with associated southwesterly mid-level jet
should continue to advance from the lower/mid MS Valley to the
Mid-Atlantic vicinity on Wednesday. A surface low initially over
northern MO is forecast to develop northeastward across the
Midwest/OH Valley and lower Great Lakes while slowly filling through
the period. A cold front extending southward from this low should
progress generally eastward across parts of the lower/mid MS Valley,
TN Valley, and Southeast through the day.

A broken line of showers/storms may be ongoing at the start of the
period across these regions along/ahead of the cold front with a
isolated/marginal severe threat. Substantial low-level moisture
return will probably make only a limited northward advance ahead of
the front. Still, diurnal heating and cooling mid-level temperatures
with the approach of the upper trough/low may promote weak
instability through Wednesday evening across the narrow warm sector.
Given strong flow aloft attendant to the previously mentioned
mid-level jet, there should be more than enough deep-layer shear to
support organized storms. Isolated strong to damaging winds appear
to be the main threat with any storms that can either persist along
the front or develop ahead of it. A brief tornado or two also cannot
be ruled out mainly early in the period, before low-level winds veer
more west-southwesterly as the primary low-level jet shifts north of
the surface warm sector and into the OH Valley by Wednesday evening.
Eventually, the cold front should outpace the modest low-level
moisture return across the TN Valley and Southeast, with a gradual
reduction in the already isolated/marginal severe threat by late
Wednesday evening as the system occludes.

..Gleason.. 11/23/2020

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