ACUS01 KWNS 251227
SWODY1
SPC AC 251226

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0726 AM CDT Thu Sep 25 2025

Valid 251300Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHEAST INTO THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND...AND
PORTIONS OF THE SOUTHWEST...

...SUMMARY...
Scattered thunderstorms are expected from the Southeast to southern
New England today. Isolated damaging winds and perhaps a tornado or
two will be possible with some of this convection. Additional
thunderstorms posing a risk for marginally severe hail and wind may
occur across parts of the Southwest.

...Southeast to Southern New York/New England...
A positively tilted upper trough extending from the Great Lakes
across the mid/lower MS Valley and southern Plains will make slow
progress eastward today towards the Atlantic/Gulf Coasts. At the
surface, a cold front will make similar eastward development, with a
moist airmass in place ahead of it. Rather poor lapse rates aloft
and cloud cover/ongoing precipitation will delay/hinder diurnal
destabilization across much of the warm sector today. A weakly
unstable airmass is still anticipated along/ahead of the front from
the Mid-Atlantic northward into southern New England. Enhanced
southwesterly low/mid-level flow may support occasional damaging
winds with thunderstorm clusters that can develop. Sufficient
low-level shear may also be in place to support some risk for a
tornado or two, mainly from parts of northern VA into southern
NY/New England. Deep-layer shear is forecast to be weaker with
southward extent from the Carolinas into GA, but greater instability
should be present owing to stronger diurnal heating. Isolated strong
to damaging winds may occur with convection that can develop
along/ahead of the front across these areas as well.

...Southwest...
A closed mid/upper-level low over central CA this morning will move
slowly east-southeastward through the period. Mid-level
west-southwesterly flow ahead of this feature should gradually
increase through the day, with large-scale ascent overspreading
parts of the Southwest by early afternoon. Scattered to numerous
thunderstorms are expected to develop initially over the higher
terrain of AZ, and subsequently develop slowly northward through the
evening. Weak to locally moderate instability coupled with modest
deep-layer shear may support an isolated hail/wind threat with the
more robust convection that develops, especially where low-level
lapse rates can become steepened through diurnal heating/mixing of
the boundary layer.

..Gleason/Grams.. 09/25/2025

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