Severe Storm Outlook Narrative (AC)
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000
ACUS03 KWNS 240729
SWODY3
SPC AC 240728

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0228 AM CDT Sun Mar 24 2024

Valid 261200Z - 271200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL GULF COAST...AND PORTIONS OF THE OHIO VALLEY...

...SUMMARY...
An isolated severe threat may persist Tuesday along/near the central
Gulf Coast, with a separate area of isolated severe potential also
developing by Tuesday afternoon across parts of the Ohio Valley.

...Central Gulf Coast...
A line of thunderstorms will likely be ongoing at the start of the
period Tuesday morning across far southeastern MS/LA into southern
AL. The airmass ahead of this convection should be only weakly
unstable, as low-level moisture will struggle to advance quickly
enough northward ahead of the line. Still, various NAM/GFS forecast
soundings across southern AL and the FL Panhandle show strong
deep-layer shear associated with a 50-70 kt southwesterly mid-level
jet over the Southeast. This shear, coupled with weak but
potentially sufficient boundary-layer instability, should be enough
for an isolated threat for damaging winds to continue through at
least Tuesday morning as the line moves eastward. Any tornado threat
will probably remain confined along and very near the coast, where
greater low-level moisture is forecast, in the presence of
sufficient but weakening low-level shear through the day. Some
guidance suggests that an isolated severe threat may also persist
Tuesday evening/night farther east across parts of the FL Panhandle
and far southwestern GA, although this potential is more uncertain
and dependent on mid to upper 60s surface dewpoints advancing inland
across these areas.

...Ohio Valley...
A very strong mid/upper-level jet, with winds around 100 kt at 500
mb, will be present over parts of the mid MS into OH Valleys Tuesday
morning. This jet will be embedded within a large-scale upper trough
encompassing much of the western/central CONUS, and associated with
a mid-level shortwave trough that is forecast to continue
east-northeastward across the OH Valley and Great Lakes through the
period. The primary surface low should be over the Upper Midwest
Tuesday morning, with a trailing cold front extending southward over
the mid/lower MS Valley. Moisture ahead of this front will likely
remain quite limited, especially with northward extent into the OH
Valley. Still, most guidance indicates that low 50s surface
dewpoints should be present late Tuesday morning into the afternoon,
potentially as far north as the IN/MI border vicinity. Cold
mid-level temperatures with somewhat steepened lapse rates aloft,
coupled with modest daytime heating, should support the development
of weak instability by early Tuesday afternoon (MLCAPE generally 500
J/kg or less). Strong deep-layer shear should foster convective
organization with any low-topped thunderstorms that can form.
Isolated severe/damaging winds appear to be the main threat with
this activity given the forecast strength of the low/mid-level
winds. But, some hail may also occur with the more robust cores.
This convection is expected to quickly weaken by early Tuesday
evening across western OH and central KY with the loss of daytime
heating.

..Gleason.. 03/24/2024

$$


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