Today’s Severe Weather Zone

William’s Severe Weather Zone for Thursday:

At the surface, a quasistationary front was drawn at 11Z across northern/western NC, northern AL, central MS, north-central LA, and parts of southeast TX. South of that front, an outflow boundary — related to persistent convection over the past 12-18 hours — was located from eastern SC to central portions of GA/AL/MS. This boundary will oscillate locally with competing influences from the prevailing, southwesterly LLJ/warm-advection plume, and outflow reinforcement by additional convection along and to its north. As such, some areas now behind the boundary may destabilize and experience the warm sector, while outflow stabilizes other areas now to its south. …Southeast… Isolated to locally scattered thunderstorms are expected to move generally eastward over the outlook area today, offering locally strong/damaging gusts, isolated hail and a marginal tornado threat. Though the area near the boundary will be the main focus for activity, isolated development also may occur in subtle, low-level corridors of lift in the warm sector — especially with erosion of already weak MLCINH by diurnal heating of a moist boundary layer. With most or all of the weak large-scale lift from the shortwave trough remaining north of the outflow boundary, upper-level influence on convective potential will be minimal today, and near-surface flow should remain light (less than 10 kt most areas) and veered (southwesterly to west-southwesterly). The latter should keep hodographs long but not particularly large nor curved, with effective SRH varying between 100-200 J/kg in times series of forecast soundings near the boundary. Still, given the strong flow aloft (e.g., 50-60 kt at 500 mb, 70-80 kt at 250 mb), broad field of related 45-50-kt effective-shear magnitudes, and deeply buoyant thermodynamic profiles (MLCAPE commonly 1000-1500 J/kg south of the boundary), expect organized multicells and at least isolated supercell threat. The convective/severe potential should diminish this evening into tonight with loss of boundary-layer heating/lapse rates, and weakening lift at all scales. ..Edwards/Gleason.. 12/30/2021 $$