ACUS02 KWNS 241731
SWODY2
SPC AC 241730

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Tue Sep 24 2024

Valid 251200Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
ALABAMA INTO THE WESTERN FLORIDA PANHANDLE...AND ACROSS MUCH OF THE
FLORIDA PENINSULA...

...SUMMARY...
Isolated severe thunderstorms capable of damaging gusts and/or brief
tornadoes are possible from southeast Alabama into the western
Florida Panhandle, and across much of the Florida Peninsula.

...Synopsis...
An amplified upper pattern, featuring a ridge extended from northern
Mexico through the northern High Plains and a trough extended from
Ontario into the Lower MS Valley, will cover the CONUS early
Wednesday. Bifurcation of the upper trough is anticipated throughout
the period, with a northern shortwave trough remaining progressive
as it moves across eastern Ontario into southern Quebec, and a
southern upper low stalling over the Mid-South vicinity. The
stalling of the southern upper low will occur as subtropical ridging
builds across the western Atlantic and a tropical cyclone enters the
eastern Gulf of Mexico. Latest forecast guidance from NHC for this
tropical cyclone, which was recently upgraded to Tropical Storm
Helene, suggests the storm will reach hurricane strength during the
day Wednesday, with additional strengthening to major hurricane
strength by early Thursday morning.

Farther west, a progressive shortwave trough is forecast to move
quickly across southern British Columbia and the Pacific Northwest,
ending the period over the northern Rockies.

At the surface, a weak front will likely extend from a low over the
Lake Huron vicinity southward through middle TN before arcing more
southwestward to another low in southeast TX. Western portion of
this front over TX and LA is forecast to remain progressive, pushing
southeastward to the western Gulf Coast by Wednesday evening.
Eastern portion of the front will stall, maintaining a more
north-south orientation from northern AL through southern Lower MI.

...Upper OH Valley through the southern Appalachians into AL, GA,
and FL Panhandle Wednesday morning into the evening...
A belt of enhanced southwesterly flow aloft is forecast to extend
through the eastern periphery of the upper low developing over the
Mid-South from the FL Panhandle northward into the Upper OH Valley.
Widespread showers and thunderstorms are anticipated within this
warm conveyor, reaching as far north as western A. However, poor
lapse rates and limited destabilization should mitigate the overall
severe potential across the majority of this region.

An area of locally higher severe potential is anticipated within a
spatially constrained corridor from southeast AL into far southwest
GA and the western FL Panhandle, just west of the primary axis of
precipitation anticipated within the warm conveyor. Here, a mix of
low 70s dewpoints, modest heating, and moderate mid-level flow could
result in a few thunderstorms capable of damaging gusts and/or a
brief tornado or two.

...Much of the FL Peninsula...
Rainbands associated with tropical cyclone Helene are forecast to
move across the FL Peninsula throughout the period. At the same
time, low to mid-level flow attendant to the cyclone will increase
as the cyclone and its expansive wind field spread northward. As a
result, vertical shear will be strong enough to support organized
storm structure. Primary mitigating factor is warm, poor lapse rate
profiles that limit buoyancy. Brief tornadoes will be possible
within any updrafts that are able to mature/persist.

..Mosier.. 09/24/2024

$$
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