SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Thu Dec 24 2020 Valid 241630Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE CAROLINAS AND SOUTHEAST VIRGINIA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN FLORIDA AND FAR SOUTHERN GEORGIA... ...SUMMARY... Severe thunderstorms are expected across portions of the Carolinas and Mid-Atlantic region this afternoon and tonight, with tornadoes and damaging wind gusts possible. ...Eastern/central Carolinas and Mid-Atlantic States... Multi-round severe convection is possible across parts of the region this afternoon into tonight, particularly for the eastern Carolinas/southeast Virginia, where semi-discrete warm sector storms this afternoon/early evening could be followed by a well-organized convective line late this evening and early in the overnight. Multi-layer cloud cover remains prevalent at midday across the region with air mass modification occurring near the coastal Carolinas where low/middle 60s F surface dewpoints are becoming more prevalent. North/northeastward-racing bands of convection over the eastern Carolinas will persist through the afternoon where the convection should gradually intensify as it becomes rooted within the increasingly moist/unstable boundary layer, although the persistent cloud cover and the possibility of a lingering warm layer aloft leads to some temporal uncertainty. Regardless, extremely strong low-level/deep-layer shear, accentuated by 55-60 kt in the lowest 1 km AGL and 300+ 0-1 km SRH, will be supportive of fast-moving supercells capable of a tornado/damaging wind risk, particularly late this afternoon through early evening. Given the magnitude of the vertical shear/SRH, a strong tornado cannot be ruled out. Otherwise, as previously mentioned, an additional round of regional severe risk will likely occur this evening into the overnight as a strongly forced convective line evolves and spreads east-northeastward across the Carolinas and coastal Mid-Atlantic/Delmarva. Damaging winds are the most probable severe hazard, although a QLCS-related tornado risk may exist as well. ...Florida/Georgia... A northeast/southwest-oriented composite convective line across southern Georgia/Florida Panhandle at late morning immediately precedes an eastward-moving cold front. Some additional moistening/diurnal destabilization will occur across the Florida Peninsula into far southern Georgia ahead of the front/convective line, with surface-based destabilization otherwise remaining minimal farther north into central/eastern Georgia. Low-level/deep-layer winds will further strengthen across the region, although low-level winds will tend to slowly veer with wind profiles trending more unidirectional over time. Even with relatively modest buoyancy, this scenario will support further organization and development of upscale-growing quasi-linear convective bands this afternoon. An isolated damaging wind/tornado risk will exist across the region through the afternoon, with the overall severe risk shifting eastward/tending to diminish toward and after sunset. ..Guyer/Lyons.. 12/24/2020
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