839
ACUS03 KWNS 151929
SWODY3
SPC AC 151928

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0228 PM CDT Wed Jul 15 2026

Valid 171200Z - 181200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
WESTERN MT/NORTHERN ID...AND ALSO ACROSS THE UPPER GREAT LAKES
REGION...

...SUMMARY...
Strong to potentially severe storms are possible on Friday across
parts of western Montana and northern Idaho, and also across parts
of the Upper Great Lakes region.

...Parts of ID/western MT...
A relatively favorable thermodynamic environment is again expected
to reside across parts of western MT and vicinity by Friday
afternoon. Relatively steep lapse rates and sufficient moisture may
result in MLCAPE increasing to near/above 1000 J/kg. A modest
decrease in mid/upper-level flow is expected compared to
D2/Thursday, as the region gradually becomes further removed from a
mid/upper-level low moving across southwestern British Columbia.
However, effective shear of 25-35 kt may develop where low-level
flow remains east-southeasterly. Scattered thunderstorms are
expected to develop during the afternoon and continue into at least
the early evening. The strongest cells/clusters will be capable of
producing isolated hail and strong to severe gusts.

...Parts of the Upper Midwest/Great Lakes...
Multiple low-amplitude midlevel vorticity maxima may move
southeastward across parts of the Upper Midwest/Great Lakes through
early evening, before a stronger shortwave trough approaches the
region by late Friday night. A frontal zone initially draped from
northern IL/IN into northern MN will begin to shift northward as a
warm front, while a cold front will move through parts of the
Dakotas and northwest MN. Diurnal heating may be somewhat muted due
to the effects of smoke, but increasing low-level moisture will
support moderate destabilization. Moderate midlevel northwesterly
flow will provide sufficient deep-layer shear for storm
organization.

Details of storm development and evolution remain uncertain across
this region, However, isolated surface-based development will be
possible near the cold front and effective warm front during the
afternoon/evening, and one or more elevated clusters may continue
into Friday night. There is a sufficient signal for storm
development within a relatively favorable environment for the
addition of 5% severe probabilities, though some adjustment will
likely be needed in subsequent updates.

...Parts of the Southeast...southern Appalachians...Ohio Valley...
Scattered to numerous thunderstorms are expected to develop Friday
afternoon, within a moist, moderately unstable, and weakly capped
environment. Localized downburst winds could occur within this
environment, though deep-layer flow/shear appears too weak to
support an organized severe threat.

..Dean.. 07/15/2026

$$