SPC 2000Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0146 PM CST Wed Dec 23 2020

Valid 232000Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE WESTERN AND CENTRAL GULF COAST REGION...

...SUMMARY...
A threat for damaging wind gusts and a few tornadoes will shift
eastward across the Lower Mississippi Valley and central Gulf Coast
region this afternoon through tonight.

...Discussion...
No changes appear necessary to the ongoing outlook, as forecast
reasoning and areas highlighted in prior outlooks continue to appear
on track.  Thunderstorms should develop across the lower Mississippi
Valley region late this afternoon, and then spread across the
central Gulf Coast region, with isolated severe weather potential.

..Goss.. 12/23/2020

.PREV DISCUSSION... /ISSUED 1030 AM CST Wed Dec 23 2020/

...Lower Mississippi Valley/Gulf Coast States...
Steady height falls are expected today as a
base-embedded/positive-tilt portion of an upper trough spreads
toward the ArkLaTex/Lower Mississippi Valley through tonight, with a
cold front moving southeastward across the region. 

Within the warm sector, showers/some thunderstorms should gradually
increase this afternoon from the middle/upper Texas coast into
Louisiana. Although cloud cover may remain semi-prevalent ahead of
the cold front, a moistening/warming boundary layer and gradual
erosion of convective inhibition suggests that this activity may
gradually become more surface-based and potentially intensify as
early as mid/late afternoon, although the cloud cover/initially
modest forcing for ascent are points of temporal uncertainty. 

Another zone of intensifying thunderstorm development is expected
immediately near the cold front as it moves southeastward across the
ArkLaTex/Mid-South late this afternoon/early evening.
Moisture/buoyancy will be comparatively lesser with northward
extend, but with very strong southwesterly winds through a deep
layer, at least some potential for damaging winds/possibly a brief
tornado will exist with near-surface-based storms late this
afternoon into tonight.

Overall, convection will become increasing prevalent/organized this
evening, including linearly organized convection near the cold front
as well as front/line-preceding semi-discrete development including
supercells, with all of this activity tending to merge overnight.
Damaging winds and a couple of tornadoes will be possible,
particularly across parts of Louisiana and far southern Mississippi.
A severe risk may exist as far east as the Florida
Panhandle/southern Alabama late tonight into early Thursday.

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