What you need to know
The NOAA Storm Prediction Center (SPC) has issued a Marginal Risk for severe thunderstorms today across parts of the western Dakotas and southern Appalachians. Isolated severe hail and damaging wind gusts are possible this afternoon through early evening as two separate weather systems move through these regions.
Where is the Marginal Risk today?
Two distinct areas are under a Marginal Risk — the lowest category on SPC's five-tier scale — for Wednesday, September 23, 2026.
The first zone covers the western Dakotas, where a mid-level trough moving northeast from Wyoming and Montana will reach the region by late afternoon. A lee trough near the Black Hills will help focus scattered thunderstorm development.
The second area spans the southern Appalachians, where a mid-level vorticity maximum is tracking southeast from the lower Ohio Valley. An inverted trough paired with higher low-level moisture will support thunderstorm development across the region this afternoon.
Neither area is expected to see widespread severe weather, but the stronger storms that do develop could produce locally damaging conditions.
Western Dakotas: Hail and wind threat this afternoon
Water-vapor imagery this morning shows a mid-level trough continuing its northeast track across Wyoming and Montana. According to the SPC Day 1 outlook, this upper disturbance will move into the western Dakotas by late afternoon and gradually weaken as it approaches the Red River Valley by Thursday morning.
A lee trough will maintain a moisture plume extending northward from the central High Plains into the western Dakotas. Model forecast soundings indicate around 1000 J/kg of MLCAPE (mixed-layer convective available potential energy) developing this afternoon, with marginally steep lapse rates supporting thunderstorm growth.
Widely scattered thunderstorms are forecast to develop as convective inhibition erodes near the lee trough and the Black Hills this afternoon. Some elongation of the wind profile may help storms organize, with the strongest cells capable of producing isolated marginally severe hail and wind gusts through early evening.
The threat window runs from mid-afternoon through early evening local time. Rapid City and communities near the Black Hills should monitor radar trends this afternoon.
Southern Appalachians: Damaging gusts possible despite cloud cover
The southern Appalachians face a different setup. A mid-level vorticity maximum will move southeast today from the lower Ohio Valley into the region, with an inverted trough focusing thunderstorm development this afternoon.
Surface dewpoints in the 60s°F will provide a regionally greater reservoir of low-level moisture compared to surrounding areas. However, extensive low cloud cover this morning will likely inhibit strong heating, lending considerable uncertainty to how much destabilization will occur.
The SPC notes that forecast soundings show limited low- to mid-level lapse rates, but perhaps 250–750 J/kg of MLCAPE may develop by mid-afternoon. Strong to locally damaging thunderstorm wind gusts may occur with the stronger storms.
SPC forecasters removed hail probabilities from the outlook due in part to the 12 UTC Nashville, Tennessee rawinsonde sounding, which depicted poor 700–500 mb lapse rates (4.8°C/km) and limited forecast buoyancy. Wind gusts remain the primary concern.
Asheville and surrounding areas fall within or near the Marginal Risk area. The threat window is this afternoon into early evening.
Yesterday's severe weather: Wind dominates the reports
The past 24 hours brought 24 wind reports, 3 hail reports, and 0 tornado reports across the United States.
Alabama led the wind report count with multiple trees and power lines downed across the northern and central portions of the state. Rogersville saw power lines fall onto a vehicle, while Montevallo experienced multiple trees down across the University of Montevallo campus, with one tree damaging a home's roof and exterior.
Texas reported severe wind gusts near Odessa and Sundown, with the Sundown WTM recording a 74 mph gust. Wyoming's Rawlins ASOS measured a 59 mph gust behind a passing thunderstorm.
Hail reports were limited to three instances of quarter-size (1.00-inch) hail in Louisiana, Utah, and Colorado.
What to expect tomorrow
SPC's Day 2 outlook shows no severe risk categories for Thursday, September 24. Thunderstorm activity will remain below severe thresholds across most of the country as the western Dakotas disturbance continues to weaken and the Appalachian system exits the region.
Conditions should remain quiet heading into the weekend across the continental United States.
Safety reminders for Marginal Risk days
Marginal Risk days often catch people off guard. While widespread severe weather is not expected, the storms that do turn severe can produce damaging conditions with little warning.
If you're in the western Dakotas or southern Appalachians this afternoon, keep an eye on radar and have a way to receive warnings. The National Weather Service may issue severe thunderstorm warnings for individual storms that meet warning criteria.
If a warning is issued for your county, move indoors and away from windows. Damaging wind gusts can snap tree limbs and down power lines in seconds, and hail can damage vehicles and property.
VORTEX is a free web app at vortexintel.app that monitors severe weather nationwide. Pro ($4.99/month) places phone calls to your phone when a tornado or flash flood warning is issued for a location you care about — calls can ring through Do Not Disturb once you enable Emergency Bypass for the number, unlike most third-party app notifications.