487
ACUS01 KWNS 120524
SWODY1
SPC AC 120523

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1223 AM CDT Mon May 12 2025

Valid 121200Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE SOUTHEAST
AND NORTHEAST MT/NORTHWEST ND...

...SUMMARY...
Isolated severe thunderstorms are possible across parts of the
Southeast today. A tornado or two, localized damaging winds, and
hail are possible. Isolated severe gusts are also possible in
northeast Montana to northwest North Dakota around early evening.

...Southeast...
The vertically stacked mid/upper low that has been nearly stationary
over the Sabine Valley will finally pivot northeastward towards
western TN through early Tuesday. A jetlet of strong mid-level
southerlies over the northeast Gulf and FL Panhandle will dampen
somewhat as it becomes centered on north FL to southeast GA vicinity
this afternoon. More probable diurnal thunderstorm development is
anticipated from the left-exit region of this jetlet westward
towards the cold-core of the stacked low. Deep-layer vertical shear
will relax with westward extent, yielding more of a pulse
strong-storm environment from Middle TN to western AL and MS.
Despite the meridional deep-layer wind profile, effective values
should be sufficient for multicell clusters and transient updraft
rotation centered on eastern AL and GA into north FL. Pockets of
modest buoyancy should support a mix of small to marginally severe
hail and strong gusts capable of isolated damaging winds. Along the
eastern periphery of this activity, a tornado or two is possible
where there remains some overlap with the western belt of enhanced
low-level flow, shifting east along the South Atlantic Coast.

Farther south, a more nebulous convective scenario is anticipated
amid extensive ongoing convection across the FL Peninsula and Keys.
Guidance differs markedly with the degree of destabilization, as
adequate boundary-layer heating will be required amid poor mid-level
lapse rates near 5 C/km. Some guidance suggests south FL has the
best chance at recovery by afternoon. As such, have opted to
maintain the level 1-MRGL risk through the entire region, mainly
driven by wind.

...Northeast MT to northwest ND...
Another day of rather deeply mixed thermodynamic profiles is
expected across this portion of the Upper MO Valley. Convective
coverage off the higher terrain of southern MT should be
substantially less than in recent days, amid deep-layer
southwesterly wind profiles. Some guidance suggests very isolated
storms could develop as low-level convergence increases in the early
evening. Should this occur, potential will exist for a few dry
microbursts producing localized severe gusts.

..Grams/Lyons.. 05/12/2025

$$