SPC 1200Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1055 PM CST Wed Feb 17 2021

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE FLORIDA
PANHANDLE INTO SOUTHERN GEORGIA AND INTO SOUTHERN SOUTH CAROLINA...

...SUMMARY...
Isolated strong to severe thunderstorms are possible from the
Florida Panhandle into southern South Carolina, with a couple
tornadoes or damaging gusts possible.

...Synopsis and Discussion...
A large upper trough will move into central parts of the CONUS, with
intense upper jet from southern TX across the TN Valley and into the
Northeast. At the surface, a cold front will extend from the central
Gulf of Mexico into the FL Panhandle Thursday morning, with a warm
front from southern GA to the SC Coast at that time.

Weak lift will persist during the day near the cold front, and along
the warm front which will become stationary by midday, then shift
south by late afternoon. The moist sector will have middle to upper
60s F dewpoints, with modest low-level lapse rates developing from
FL into southeast GA with heating.

Despite the moist air mass, instability will be marginal due to warm
midlevel temperatures, with MLCAPE of 500-1000 developing by 21Z.
Bands of storms are likely to be ongoing from the FL Panhandle into
southwest GA in the morning, and this may in fact be the maximum
threat for the day as large-scale lift generally decreases with
time. Effective SRH may exceed 300 m2/s2 near the weak surface low
over the FL Panhandle, with a supercell or two possible with tornado
risk. 

Farther north into coastal SC, the severe risk will be lower, and
dependent on whether the better low-level moisture remains over land
before the cooler air infiltrates from the north after 18Z. The most
likely scenario here appears to be for evening storms to become
elevated above this aforementioned boundary, with only a conditional
risk.

..Jewell/Wendt.. 02/18/2021

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