Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1158 PM CST Tue Dec 10 2024
Valid 111200Z - 121200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
SOUTHERN NEW ENGLAND ALONG THE ATLANTIC COAST SOUTH TO FAR
NORTHEASTERN NORTH CAROLINA...
...SUMMARY...
Isolated severe thunderstorms are possible today across the East
Coast States, as far north as southern New England. The most
probable area for a few tornadoes and damaging winds appears to be
centered on eastern North Carolina from midday onward.
...Synopsis...
South of a closed low over the western Ontario area, a
strong/high-amplitude trough initially aligned roughly along the
Mississippi Valley will shift rapidly eastward and then
northeastward, acquiring substantial negative tilt with time.
At the surface, a cold front will sweep eastward, clearing most of
the coast through the afternoon, and eventually shifting southward
and off the southern Florida coast/the Keys during the evening
hours.
...Southern Atlantic Coast states...
As a cold front advances eastward across the East Coast states
through the morning and afternoon hours, strong ascent forced by the
potent/advancing upper trough will support showers and embedded
thunderstorms within the weakly unstable warm sector.
Despite the thermodynamic deficiencies that are expected, a high-end
wind field will exist, with flow veering gradually and increasing
rapidly in magnitude with height. Resulting shear will favor
supercells with any semi-discrete storms, while linear organization
is also expected in an overall mixed-mode evolution. Along with
potential for damaging wind gusts, a few tornadoes are also
expected. The greatest risk appears to exist across the eastern
North Carolina/Coastal Plain area, during the afternoon. Weaker
flow aloft farther south into Florida suggests limiting southern
extent of the SLGT risk area to the far northeastern South Carolina
vicinity, similar to prior forecasts. Risk will end in most areas
by late afternoon, as the front moves offshore in all areas except
Florida, before finally clearing the Peninsula after dark.
...Mid-Atlantic region to southern New England...
As a surface low deepens over the central Appalachians region and
moves quickly northward through the day, low-topped convection near
the trailing cold front may evolve into broken linear segments. The
boundary layer is forecast to remain stable, with potential a couple
hundred J/kg CAPE above 850 to 900mb, sufficient for
occasional/sporadic lightning.
Meanwhile, extremely strong low-level flow is expected, which will
support very fast-moving convection. Given the strongly dynamic
synoptic setup as the upper trough takes on increasingly negative
tilt, the overall setup suggests locally strong wind gusts despite
the surface-based stable layer. As such, will raise damaging wind
probability to 15% and thus introduce SLGT risk to parts of southern
New England and coastal areas of the Mid-Atlantic region, with some
gusts in excess of 60 MPH expected.
..Goss/Moore.. 12/11/2024
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