LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1238 AM CDT Sat Mar 25 2023
Valid 251200Z - 261200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE LOWER
GREAT LAKES INTO THE MID-ATLANTIC STATES...AND FOR PORTIONS OF THE
SOUTHEAST...
...SUMMARY...
Isolated severe thunderstorms are possible from the Lower Great
Lakes into parts of the Mid-Atlantic states. A separate area of
potential isolated severe thunderstorms will encompass parts of the
Southeast.
...Synopsis...
A potent mid-level trough over the middle MS Valley early this
morning will move northeast and evolve into a closed mid-level low
over the central Great Lakes by early evening. A belt of intense
west-southwest mid-level flow will extend from the southern U.S.
into the Mid-Atlantic states/Northeast. At the surface, a cyclone
initially over northeast IN will develop north-northeast and deepen,
reaching Lake Huron by late afternoon/early evening, and then
subsequently weaken/occlude tonight. A surface front will sweep
east across the OH Valley and into the Lower Great Lakes during the
day, with the trailing portion of the boundary moving through a
large part of the Southeast but stalling and becoming draped over
the central Gulf Coast.
...Lower Great Lakes into the Mid-Atlantic states...
In wake of some early day clouds, diurnal heating and a narrow plume
of lower 50s F dewpoints ahead of the front over the upper OH Valley
will act to weakly destabilize the boundary layer (200-400 J/kg
MLCAPE). Strong large-scale forcing for ascent --due in part to
strong, differential cyclonic vorticity advection-- will promote
isolated to scattered thunderstorms from the lower Great Lakes to
perhaps as far south as WV/VA/MD. Strong low-level shear profiles
and cold mid-level temps may yield a low-topped supercell risk from
eastern OH into western PA and perhaps western NY. Other strong to
locally severe storms may develop during peak heating farther
south/southeast and yield a marginal wind-damage threat. This
activity will likely subside by early evening coincident with the
loss of heating.
...Southeast...
A band of showers/thunderstorms will likely be ongoing early this
morning across parts of GA into the southern Appalachians. A
lingering strong to locally severe risk may accompany this activity
before weakening by late morning. Models show a reservoir of
seasonably rich low-level moisture and relatively steep mid-level
lapse rates across AL/GA into SC. Although much of the large-scale
forcing for ascent will be displaced to the north of the region,
neutral mid-level heights and the heating of a moist boundary layer
becoming moderately unstable may favor isolated thunderstorms
redeveloping during the afternoon. If residual morning convection
re-intensifies or additional afternoon storms develop, the presence
of strong deep-layer shear will favor storm organization and a
severe risk. Models vary considerably on the placement/coverage of
storms in this overall weakly forced setup. Nonetheless, at least
an isolated risk for all hazards seems warranted. This potential
storm activity will likely weaken by early evening.
..Smith/Weinman.. 03/25/2023
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