SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CST Wed Feb 17 2021 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE FLORIDA PANHANDLE...SOUTHEASTERN ALABAMA...SOUTHERN/CENTRAL GEORGIA...AND COASTAL SOUTH CAROLINA... ...SUMMARY... Isolated strong to severe thunderstorms may occur across parts of the Southeast on Thursday. A couple tornadoes and isolated damaging wind gusts should be the main threats. ...Southeast... A large-scale upper trough is forecast to move eastward from the Plains to the MS Valley vicinity on Thursday. A belt of enhanced mid/upper-level southwesterly winds will overspread much of the Southeast to the Mid-Atlantic through the period. At the surface, a weak low over the north-central Gulf of Mexico should develop northeastward across the FL Panhandle and into southern GA by Thursday evening. A warm front is forecast to lift northward across southern GA in the same time frame. A cold front attendant to the surface low will eventually sweep eastward across northern FL and southern GA Thursday afternoon/evening and continuing through the overnight. A broken band of strong to potentially severe storms may be ongoing Thursday morning across parts of the western FL Panhandle and vicinity. Low-level moisture is forecast to gradually increase across the warm sector ahead of this morning convection, with mid to upper 60s surface dewpoints likely by mid afternoon. Diurnal heating will probably be fairly muted, but it should still support weak boundary-layer instability along/south of the warm front by Thursday afternoon. MLCAPE around 250-750 J/kg appears probable, with poor mid-level lapse rates likely limiting more robust destabilization. Much of the large-scale forcing associated with the approaching upper trough and related mid/upper-level jet may remain mostly to the north of the surface warm sector. Still, strong flow aloft will likely foster 40-50 kt of effective bulk shear, which will be more than sufficient for organized severe storms. Current expectation is for storms to spread eastward through the afternoon across the FL Panhandle and southern GA, eventually reaching parts of central/eastern GA and coastal SC by early Thursday evening. Given the weak but adequate instability and strong low/mid-level flow, isolated damaging winds may occur with both discrete and linear convection. A couple tornadoes also appear possible with any supercells that can form, as a 40-45 kt south-southwesterly low-level jet will overlie much of the warm sector through the day, enhancing effective SRH. This tornado threat may focus along/near the northward-developing warm front in southern/central GA and coastal SC. Storms should eventually encounter a less unstable airmass with eastward extent into northern FL and coastal GA, and a general weakening trend should occur Thursday evening/night. Finally, low-level moisture return father north across SC and eastern NC appears more muted in latest guidance, suggesting any isolated/marginal wind threat should remain close to the coast. ..Gleason.. 02/17/2021
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