Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Mon Sep 15 2025
Valid 151300Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM WYOMING
INTO WESTERN SOUTH DAKOTA...OVER FAR NORTHERN MINNESOTA...AND
NORTHEAST NORTH CAROLINA...
...SUMMARY...
Isolated severe gusts are possible across Wyoming into western South
Dakota this afternoon to early evening. Isolated severe hail and
damaging wind are possible across far northern Minnesota in the
early to mid-afternoon. A brief tornado is possible in the northeast
North Carolina vicinity in the early morning Tuesday.
...WY to western SD...
A shortwave trough over western ID will move east across WY/western
SD during the day, as several embedded vorticity maxima contribute
regions of enhanced ascent. Steep mid-level lapse rates of 8-9 deg
C/km, combined with diurnal heating, will result in MLCAPE of a few
hundred J/kg across much of the area. Despite weak buoyancy, the
favorably-timed ascent will contribute to thunderstorm
development/intensification this afternoon as storms approach
northeast WY/western SD. A deep and well-mixed boundary layer will
lead to high-based convection capable of isolated strong/damaging
gusts through early evening, with intensities diminishing thereafter
as nocturnal cooling commences.
...Northeast NC/southeast VA vicinity...
A surface low southeast of Cape Hatteras is forecast to move towards
the NC coast through 12z Tuesday, with a belt of stronger low-level
flow developing north/northwest of the low. Variability remains
regarding the forecast location of the low and strength of low-level
winds, however a conditional risk for a tornado would exist early
Tuesday morning with stronger convective elements, should sufficient
low-level hodograph curvature develop, as high theta-e air is
advected west across the northeast NC/southeast VA vicinity.
...Far northern MN...
Thunderstorm development is expected this afternoon within a
northwest-southeast oriented arc from southeast Manitoba across
northeast Ontario as a shortwave trough becomes increasingly
negatively tilted while lifting northeast. Although development
south of the international border is uncertain, some CAM guidance
suggest isolated development is possible. Moderate buoyancy and
effective shear of 35-40 kts over far northern MN suggests a
conditional risk for severe wind/hail would exist should storm
development occur in this area.
...MO/AR vicinity...
A few strong gusts will be possible again today with pulse-type
storms within a weakly-sheared but strongly unstable (MLCAPE of
2500-3000 J/kg) environment.
..Bunting/Broyles.. 09/15/2025
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