SPC 0830Z Day 3 Outlook

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0220 AM CST Tue Dec 29 2020

Valid 311200Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM FAR SOUTHEAST
TEXAS INTO THE CENTRAL GULF COAST STATES...

...SUMMARY...
Severe thunderstorms associated with a tornado threat and wind
damage will be possible Thursday into Thursday night from far
southeast Texas into the lower Mississippi Valley and across the
central Gulf Coast States.

...Southeast Texas/Lower Mississippi Valley/Central Gulf Coast
States...
An upper-level low will move from northern Mexico into the southern
Plains on Thursday. Divergent flow aloft will overspread eastern
Texas and Louisiana as the negatively-tilted system deepens. A large
cluster of thunderstorms appears likely to be ongoing in southeast
Texas at the start of the period. This convection is forecast to
move eastward as a low deepens and moves northeastward into the
Arklatex. Although instability will be weak along the attendant
surface trough, strong deep-layer shear will create conditions
favorable for severe storms. Lift associated with a mid-level jet,
rounding the base of the upper-level system, will provide additional
support for organized storms. As the mid-level jet moves eastward
across the Lower Mississippi Valley on Thursday, thunderstorm
development is expected to occur across parts of Louisiana and
Mississippi. 

Instability is forecast to gradually increase across the moist
sector, which should be located from Louisiana to southwestern
Alabama. Discrete thunderstorms that develop ahead of the cold front
across the moist sector could have a wind damage and tornado
potential. During the late afternoon, the most favorable area would
be in far southeast Louisiana, where the models maximize instability
at the northern end of the moist axis. The corridor of maximized
low-level moisture is forecast to shift eastward across southern
Mississippi and southern Alabama during the evening and overnight
period. Models suggest the possibility of a convective line located
along the moist axis. This line would be associated with a continued
wind damage and tornado threat during the overnight period.

..Broyles.. 12/29/2020

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