SPC 1630Z Day 1 Outlook

Day 1 Outlook Image

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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