652
ACUS02 KWNS 171730
SWODY2
SPC AC 171729

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 PM CDT Sun Aug 17 2025

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITHIN THE
CENTRAL/NORTHERN PLAINS AND UPPER MIDWEST...

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Upper Midwest on Monday. Isolated to widely scattered
storms could produce large hail and severe winds in parts of the
central/northern Plains.

...Northern/Central Plains...
Isolated to widely scattered storms to develop either along a weak
surface trough, within the terrain in eastern Wyoming/Black Hills,
or a cold front near the Nebraska/South Dakota border. Strong
buoyancy and effective shear of 30-40 kts will allow for the
stronger storms to be organized. Large hail and severe winds would
be the expected hazards. There is some potential for a more
organized cluster of storms to progress eastward. This would most
likely occur near the cold front during late afternoon/evening.
However, a very weak low-level jet and uncertain cold pool
organization keeps confidence too low for any increase in wind
probabilities.

...Upper Midwest...
Showers/thunderstorms are expected to be ongoing Monday morning.
This will have an impact on where the greatest destabilization will
occur during the afternoon. Furthermore, the region will be in the
wake of a departing shortwave trough/MCV with mid-level ascent being
nebulous and uncertain. Current guidance suggests the greatest
potential for afternoon storms will exist in parts of
central/southern Wisconsin into northern Illinois. There, some
surface heating and low-level lift near a weak surface low/triple
point could promote widely scattered to scattered thunderstorms.
While the exact placement of this activity remains uncertain, the
environment would support marginal supercells and multicell clusters
with a primary hazard of damaging winds.

Farther southwest into Iowa, strong buoyancy is expected to develop
south of any outflow from morning activity. MLCAPE around 3000 J/kg
would support a threat for isolated wind damage even with weaker
effective shear than farther north. However, with little in the way
of mid-level ascent and uncertain low-level forcing gives low
confidence in storm coverage.

...Southwest into central Montana...
Though a ridge will be building into the northern Rockies,
sufficient moisture  may promote thunderstorm development in the
higher terrain. Flow aloft will be strong enough to support at least
marginally organized storms. However, it is not clear how intense
storms will be given some signal for moisture to mix out during the
afternoon. Strong, gusty outflow winds are possible, but confidence
in severe potential remains low.

..Wendt.. 08/17/2025

$$