SPC May 12, 2025 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0741 AM CDT Mon May 12 2025

Valid 121300Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
MONTANA AND NORTHWEST NORTH DAKOTA...

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

...Southeast States...
The persistent vertically stacked mid/upper low that has been nearly
stationary over the Sabine Valley/Lower Mississippi River Valley
will finally accelerate northeastward towards western Tennessee
through tonight. A jetlet of cyclonically curved mid-level
southerlies over the northeast Gulf and Florida Panhandle will
dampen somewhat as it becomes centered on north Florida to southeast
Georgia 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 Tennessee to
western Alabama and Mississippi. Despite the meridional deep-layer
wind profile, effective shear should be sufficient for multicell
clusters and transient updraft rotation centered on eastern Alabama
and Georgia into north Florida. 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, including
South Carolina into both western and near-coastal North Carolina.

Farther south, a more nebulous convective scenario is anticipated
amid extensive ongoing convection across the Florida 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. But some guidance suggests
south-central/southern Florida has the best chance at recovery by
afternoon, although low-level winds will tend to be veering with a
likely diminishing trend of low-level SRH.

...Northeast Montana/northwest North Dakota...
Another day of rather deeply mixed thermodynamic profiles is
expected across the region. Isolated thunderstorms are most probable
from mid-afternoon into evening with development near/behind an
eastward-advancing front. Overall convective coverage off the higher
terrain of southern Montana should be substantially less than in
recent days, amid deep-layer southwesterly wind profiles. The
potential will exist for a few dry microbursts producing localized
severe-caliber wind gusts.

..Guyer/Dean.. 05/12/2025

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