236
ACUS03 KWNS 200731
SWODY3
SPC AC 200730

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Thu Aug 20 2026

Valid 221200Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
OHIO VALLEY TO THE LOWER GREAT LAKES...AND OVER PARTS OF THE
NORTHWEST...

...SUMMARY...
Afternoon storms may produce marginal hail or wind gusts from the
Upper Ohio Valley to the Lower Great Lakes, and over parts of the
Northwest on Saturday.

...Upper OH Valley to Lower Great Lakes...
An upper trough will dig across the Great Lakes/OH Valley on
Saturday with a 50 kt backside speed max in the midlevels from MN
into IL. While winds aloft will be weaker farther east, cooling
aloft will overspread the entire region. Meanwhile, a cold front
will push across Lower MI, IN and OH during the day, with a plume of
1500 J/kg MLCAPE developing. This will support clusters of storms
with strong to severe gust potential. The cool temperatures aloft
and effective shear to 30 kt may also support marginal hail.

...Parts of eastern WA...ID...western MT...
A shortwave trough will move across the Northwest on Saturday, with
a 50-60 kt midlevel speed max moving across the region along with
cooling aloft. This trough will steepen midlevel lapse rates,
resulting in an unstable air mass as daytime heating occurs. Storms
are likely to form near the surface trough, and spread across
northern ID and into western MT through the evening and overnight.
The strengthening wind fields combined with favorable lapse rates
will support cells with marginal hail, as well as corridors of
strong wind gusts.

..Jewell.. 08/20/2026

$$