SPC 1730Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1129 AM CST Thu Dec 10 2020

Valid 111200Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL
AND EAST TX INTO PORTIONS OF SOUTHEAST OK...WESTERN/CENTRAL AR...AND
NORTHWEST LA...

...SUMMARY...
Thunderstorms associated with marginally severe wind gusts will be
possible on Friday across parts of central/east Texas, southeast
Oklahoma, western/central Arkansas, and northwest Louisiana.

...Synopsis...
A broad and deep upper trough is forecast to be in place across the
western and central CONUS early Friday morning. An embedded lead
shortwave trough will likely be centered over the central and
northern southern Plains with another shortwave trough farther west
over the Four Corners region. The lead shortwave will likely dampen
as it moves northeastward within more confluent flow. The Four
Corners shortwave is expected to continue eastward into the
central/southern Plains while becoming increasingly negatively
tilted. 

At the surface, a low associated with the lead shortwave will likely
be centered over central OK. A cold front will extend northeastward
from this low into Lower MI and southwestward into the southern TX
Panhandle. Northern portion of this front will make modest
southeastward progress throughout the day while the surface low
tracks gradually northeastward along it. Expectation is for the
surface low to end the period over IL. Southern portion of the front
will sweep southeastward/eastward across eastern OK, north/central
TX, and the Arklatex, ending the period over the Lower MS Valley. 

...Central/North-Central/East TX into the Arklatex...
A broad warm sector with isolated thunderstorms is expected to cover
much of central and eastern TX/OK early Friday morning, ahead of the
second, stronger Four Corners shortwave trough mentioned in
synopsis. Modest low-level moisture advection is anticipated
throughout the day within this warm sector, with mid 50s dewpoints
likely reaching into southeast OK and central OK. Any 60s dewpoints
will likely stay south of the TX/OK Red River border. Enough
low-level moisture will likely be present for modest elevated
instability (for parcels rooted around 850-mb) and continued
potential for a few thunderstorms within the warm sector. However,
severe potential will be limited by the elevated nature of the
storms and transient updraft character promoted by modest
instability.

Even so, some severe potential may be realized later in the
afternoon and evening as the cold front pushes across the region.
The increased potential for surface-based storms coupled with
strengthening wind fields (particularly around 850-mb) could result
in updrafts deep and persistent enough to produce damaging wind
gusts. Tornado threat currently appears less than 2% due to lack of
potential within the warm sector and more favored linear mode along
the front. 

Additionally, there is a low probability (i.e. lower than 5%) for
updrafts strong enough to produce hail along the front in
north-central/northeast TX. This threat will depend on just how much
filtered daytime heating can be realized between the warm conveyor
belt and the approaching cold front. Higher confidence in these
mesoscale details could result in the inclusion of hail
probabilities in later forecasts.

..Mosier.. 12/10/2020

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