Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 AM CDT Wed Aug 12 2026
Valid 121300Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN/CENTRAL PLAINS TO THE LOWER OHIO VALLEY...
...SUMMARY...
Scattered severe thunderstorms are possible today through this
evening from parts of the mid Mississippi Valley and lower Ohio
Valley into portions of the central and northern High Plains.
Severe gusts and large hail are the primary hazards.
...IA to OH Valley...
Radar/satellite imagery this morning show several thunderstorm
clusters ongoing from IA into the OH Valley. The most notable
thunderstorm cluster is over far eastern IA and is moving into
central and northern IL this morning. The airmass downstream of
this activity is very moist and extremely unstable [reference the 12
UTC Davenport, IA raob (4300 J/kg MLCAPE)], and it is located near
the terminus of a 35-kt west-southwesterly LLJ over northern MO.
Expecting a gradual intensification of storms this morning across IL
with a risk for scattered severe gusts and associated wind damage.
Considerable uncertainty remains regarding the eventual evolution of
additional storm clusters over parts of the Midwest through this
afternoon. Outflow from morning showers/storms over eastern IN into
central KY will likely inhibit appreciable severe risk farther east
across parts of the OH Valley. Nonetheless, a moist and
destabilizing boundary layer will lend a risk for scattered wind
damage and isolated large hail with the stronger storms through the
late afternoon and evening.
...Northern/Central Plains...
East/southeasterly low-level flow will maintain modest moisture
across the Dakotas, increasing with southward extent across NE into
northern KS. Near-60 F dewpoints will likely spread westward into
eastern CO/WY/MT beneath steep lapse rates. Ample heating will
result in moderate buoyancy and 30+ kt effective shear---supporting
some organization to the scattered thunderstorms forecast to develop
later this afternoon/evening. Initial cells will pose a threat for
large hail and severe gusts. Some clustering may occur during the
evening but confidence remains low regarding specific corridors
where the severe threat will focus.
...Lower MI into NY/PA/NJ...
A belt of stronger northwesterly flow aloft will extend from Lower
MI into NY/PA today. A seasonally moist/unstable airmass will be in
place. Vertically veering wind profiles will foster 35+ kt
effective shear magnitudes, while hodographs are fairly elongated.
Midlevel lapse rates will remain modest, with MLCAPE around
1000-1500 J/kg expected. Isolated to widely scattered storms will
pose a risk for damaging gusts and marginally severe hail.
...TN Valley/Southeast...
Thunderstorms are expected to develop by midday within a very moist
and strongly unstable airmass. Deep-layer northwesterly flow will
remain weak, but steepened 0-2 km lapse rates and high PW (near 2
inches) will support an isolated risk for some stronger water-loaded
downdrafts capable of wind damage.
...Lower CO River Valley...
Model guidance shows widely scattered storms developing this
afternoon near a weak upper trough analyzed this morning via
water-vapor imagery. Some of the stronger thunderstorm downdrafts
may be capable of isolated severe gusts.
..Smith/Kerr.. 08/12/2026
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