Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk
Area (sq. mi.)
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
SPC AC 220537
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1237 AM CDT Wed Sep 22 2021
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
OHIO VALLEY AND CENTRAL APPALACHIANS...
Scattered strong to severe storms will spread across portions of the
Ohio Valley and central Appalachians. Damaging winds are the
primary threat, though a few tornadoes could be noted.
...OH Valley/Central Appalachians...
Early-morning water-vapor imagery depicts a well-defined mid-level
short-wave trough digging into the lower MO Valley. This feature is
forecast to track across the lower OH Valley during the day as an
80kt 500mb speed max translates across the TN Valley into northern
KY by 18z. During the latter half of the period, this feature should
deepen with a closed low advancing into northwest OH. Strong
mid-level 12hr height falls will precede this upper trough with wind
profiles/shear expected to increase markedly across eastern OH into
Latest NAM guidance suggests partial clearing will allow strong
boundary-layer heating along a corridor extending from western VA
into eastern OH/western PA. This will result in steepening low-level
lapse rates (7 C/km) immediately ahead of the front. Forecast
soundings by early afternoon across eastern OH exhibit MLCAPE in
excess of 1000 J/kg and lifted parcels should easily convect, both
along the advancing front and ahead of the boundary. While
supercells are expected, especially with more discrete updrafts
ahead of the wind shift, strong lift should contribute to a forced
squall line that will advance across the upper OH Valley in response
to the strong short wave. While damaging winds will be the primary
concern, low-level SRH and bulk shear favor some tornado potential.
Greatest risk for tornadoes will be during the afternoon into early
evening hours when the boundary layer will be most buoyant,
primarily over eastern OH/western PA.
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z