ACUS02 KWNS 100543
SWODY2
SPC AC 100541

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1241 AM CDT Tue Sep 10 2024

Valid 111200Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN SOUTH LA TO THE
COASTAL WESTERN FL PANHANDLE...

...SUMMARY...
A few tornadoes are possible across the central Gulf Coast vicinity
on Wednesday into Wednesday night, in association with Tropical
Cyclone Francine.

...Central Gulf Coast...
Per latest NHC forecasts and ensemble guidance, Tropical Storm
Francine is expected to become a hurricane over the northwest Gulf
and make landfall along the LA coast around Wednesday evening. A
low-probability tornado threat with outer-band convection should
reach coastal LA by Wednesday morning. The more favorable overlap of
strengthening low-level shear/SRH and intrusion of deeper tropical
moisture (surface dew points in the mid/upper 70s F) is expected
during the afternoon and evening across parts of south-central to
southeast LA and far southeast MS/southwest AL. As the TC progresses
inland and weakens Wednesday night, some broadening of the favorable
SRH/surface-based buoyancy environment should spread east into the
coastal FL Panhandle. The northern extent of a low-probability
tornado threat remains uncertain, with surface-based buoyancy
potentially remaining quite limited into parts of central MS and
interior south AL Wednesday night.

...Interior Northwest to the northern High Plains...
A shortwave trough will progress inland from the coastal Pacific
Northwest, likely reaching the northern Rockies to central Great
Basin by 12Z Thursday. Large-scale ascent and cooling mid-level
temperatures attendant to the approaching trough will support
scattered thunderstorms across the interior Northwest on Wednesday
afternoon. While the bulk of strong mid-level flow will remain
displaced west of the shortwave trough, moderate enhancement of
southwesterlies will occur ahead of it. This should be adequate for
marginal updraft rotation amid weak surface-based buoyancy. Isolated
strong to localized severe gusts along with small to marginally
severe hail will be possible into the early evening.

Separately, isolated to widely scattered high-based, low-topped
thunderstorms should form in the late afternoon along a lee trough
towards a quasi-stationary front over the northern High Plains.
Meager buoyancy and modest deep-layer shear within a meridional wind
profile suggest sporadic severe gusts in microbursts will be the
main threat. Along the immediate north of the front, a confined
corridor of greater moisture/instability should be in place during
the afternoon/evening, but capping will likely limit surface-based
development. A few stronger elevated storms will be possible into
Wednesday night, but potential for severe hail appears negligible.

..Grams.. 09/10/2024

$$
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