SPC 1200Z Day 1 Outlook
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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