Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0726 AM CDT Wed Sep 23 2026
Valid 231300Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
WESTERN DAKOTAS AND SOUTHERN APPALACHIANS...
...SUMMARY...
Isolated severe thunderstorms are possible this afternoon across
parts of the western Dakotas and southern Appalachians.
...Western Dakotas...
Water-vapor imagery this morning shows a mid-level trough moving
northeast across WY/MT. This upper disturbance will move into the
western Dakotas by late afternoon and gradually deamplify as it
reaches the Red River Valley by daybreak Thursday. A lee trough
will facilitate the maintenance of a moisture plume extending
northward from the central High Plains into the western Dakotas.
Model forecast soundings show around 1000 J/kg MLCAPE developing
with marginally steep lapse rates. Widely scattered thunderstorms
are forecast to develop as convective inhibition erodes in the
vicinity of the lee trough and the Black Hills this afternoon. Some
elongation of the hodograph may aid in some storm organization
potential, with the stronger thunderstorms perhaps yielding an
isolated risk for marginally severe hail/gusts through early
evening.
...Southern Appalachians...
A mid-level vorticity maximum will move southeast today from the
lower OH Valley into the southern Appalachians. An inverted trough
co-located with a regionally greater reservoir of low-level moisture
(i.e., surface dewpoints in the 60s deg F), will focus thunderstorm
development this afternoon. Extensive low cloud cover will likely
inhibit strong heating and lends considerable uncertainty regarding
destabilization and the potential for stronger thunderstorm
development. Forecast soundings show that despite limited low to
mid-level lapse rates, perhaps 250-750 J/kg MLCAPE may develop by
mid afternoon. Strong to locally damaging thunderstorm gusts may
occur with the stronger storms. Have removed low hail probabilities
due in part to the 12 UTC Nashville, TN raob depicting poor 700-500
mb lapse rates (4.8 deg C/km) and limited forecast buoyancy.
..Smith/Mead.. 09/23/2026
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