ACUS02 KWNS 160607
SWODY2
SPC AC 160605

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
0105 AM CDT Thu Jul 16 2026

Valid 171200Z - 181200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF NORTHERN IDAHO AND WESTERN MONTANA AS WELL AS PORTIONS OF THE
UPPER MIDWEST AND NORTHERN GREAT LAKES...

...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 the Upper Midwest and Great Lakes ...

A subtle mid-level vorticity maximum evident in the 16/00 UTC
guidance is expected to move southeastward across northern Minnesota
and the Upper Great Lakes on Friday morning, supporting ongoing
thunderstorms across the Arrowhead of Minnesota. This activity
should spread southeastward through the morning with at least a
marginal severe hail/wind threat. 

During the day, a surface frontal zone draped from northern
Illinois/Indiana should begin to lift northward, ahead of a surface
cold front moving through the northern Plains. To the south of the
warm front and ahead of the cold front, diurnal heating may be
somewhat muted by smoke and residual cloud cover from morning
convection. However, increasing low-level moisture should still
support moderate destabilization by the afternoon, especially where
stronger diurnal heating occurs. Moderate mid-level northwesterly
flow will provide enough vertical shear to support organized storms.

As the stronger mid-level wave approaches the region during the late
afternoon and evening, some potential exists for surface-based
thunderstorm redevelopment -- especially near the intersection of
the cold front and effective warm front. Large hail and strong
thunderstorm winds will be possible with these storms, and the
low-level wind field would support at least some potential for a
tornado with any sustained surface-based storm during the evening.
With time this activity should evolve into one or more clusters of
thunderstorms moving southeast overnight across the northern Great Lakes.


... Western Montana and Northern Idaho ...

A relatively favorable thermodynamic environment will once again be
in place across parts of western Montana and northern Idaho by
Friday afternoon. Relatively steep low- and mid-level lapse rates,
sufficient moisture, and diurnal heating should support afternoon
SBCAPE values in the 1000-1500 J/kg range, as suggested by the
20260716 00UTC HREF. Mid-/upper-level flow will be less than in
previous days as the region becomes increasingly displaced from a
mid-/upper-level trough/low moving northward into southwest Canada.
That said, effective-layer shear on the order of 25-35 knots will be
possible, especially where east/southeasterly surface winds are maintained.

Scattered thunderstorms are expected to develop during the afternoon
and evening hours. The strongest thunderstorm clusters will be
capable of large hail. Strong to severe thunderstorm gusts will be
possible as well, especially where convective outflows can
consolidate amid the steep low-/mid-level lapse rates. Most 16/00
UTC HREF members show explicit convective outflow gusts approaching
60 mph, supporting a localized severe threat.

If convective coverage appears greater than currently forecast,
severe probabilities may need to be increased in subsequent outlooks.


... Ohio Valley ...

Scattered to numerous thunderstorms are expected to develop during
the 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. Additionally, 16/00 UTC guidance
suggests early initiation across the region, which would limit the
development of widespread steep low-level lapse rates, which may
provide some limit on a more widespread, storm-scale driven wind
threat. This region will continue to be evaluated in subsequent outlooks.

..Marsh.. 07/16/2026

$$
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