Day 1 Convective Outlook
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Summary
Isolated severe thunderstorms with the potential for hail and damaging wind gusts are possible this afternoon across parts of the western Dakotas and the southern Appalachians.
Product Text
000 ACUS01 KWNS 231228 SWODY1 SPC AC 231226 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 $$