SPC 2000Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0129 PM CST Fri Dec 11 2020

Valid 112000Z - 121200Z


A few strong or damaging wind gusts are possible from eastern Texas
into western Louisiana and southwest Arkansas from late afternoon
into early evening.

Little change was made to the previous outlook, with a continued
low-end isolated severe risk later today. The main change from the
prior outlook was to remove northwestern parts of the Marginal due
to lack of instability. Otherwise, storms are expected to form over
eastern TX after 21Z, and persist through evening as they move into
LA and southwest AR. Some of the storms may fail to become surface
based due to existing rain and cool temperatures, which would
minimize tornado threat. The higher theta-e surface air will extend
from southeast TX into southwest LA through evening.

..Jewell.. 12/11/2020

.PREV DISCUSSION... /ISSUED 1031 AM CST Fri Dec 11 2020/

...East Texas into the lower Mississippi Valley...

As of late this morning a cold front was situated from a weak
surface low in northeast KS southwestward through southeast OK to
just north of Midland in west TX. A weakly unstable warm sector is
present across central through east TX where surface dewpoints range
from mid 50s in north central TX to mid 60s F near the coast.
Widespread clouds and ongoing areas of showers with embedded
isolated thunderstorms in addition to the modest low-level moisture
will considerably limit instability with MLCAPE from 200-400 J/kg.
Forcing for ascent along the warm conveyor belt associated with a
progressive low-amplitude shortwave trough will maintain this area
of precipitation eastward into the lower MS Valley. Vertical wind
profiles and the most favorable low-level hodographs for organized
severe storms will reside in the warm sector where instability is
meager, limiting the overall severe threat. The best chance for a
few stronger storms might evolve along the southern portion of the
conveyor belt from east central and southeast TX into far western LA
by early evening where the influx of higher theta-e air will be
greatest. These storms may pose a modest risk for mainly a couple of
strong wind gusts. Low-level hodographs will also remain sufficient
for a conditional risk for a brief tornado. 

A narrow corridor of clearing and modest destabilization will occur
west of the cloud shield and just east of the cold front where a few
thunderstorms might develop along the front from north central into
northeast TX. However, weakening and veered low-level winds suggest
the severe threat should remain limited to a brief strong wind gust
or two at best.

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