Subj : DAY2SVR: Nws Storm Predic
To   : All
From : Mike Powell
Date : Sun Aug 17 2025 10:11:07

ACUS02 KWNS 170536
SWODY2
SPC AC 170534

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1234 AM CDT Sun Aug 17 2025

Valid 181200Z - 191200Z

....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE NORTHERN PLAINS EASTWARD TO THE UPPER MISSISSIPPI VALLEY AND
WESTERN GREAT LAKES...

....SUMMARY...
Thunderstorms with potential for isolated severe wind gusts and hail
will be possible on Monday over parts of the central and northern
Plains eastward into the upper Mississippi Valley and western Great
Lakes.

....Central and Northern Plains/Mid Missouri Valley...
At mid-levels, a ridge will build over the northern Plains on
Monday, as flow over much of the north-central U.S. remains from the
west-northwest. At the surface, a post-frontal airmass will be in
place over much of the central and eastern Dakotas. Along the
southern and western periphery of this airmass, moderate instability
will likely develop by afternoon from parts of eastern Montana
southeastward into Nebraska. Large-scale ascent will likely remain
limited over much of the region, helping to keep convective
development isolated. Although deep-layer shear should remain below
35 knots in most areas, low to mid-level lapse rates will be steep.
This could be enough for a marginal severe threat, mainly in the
late afternoon and early evening. Severe wind gusts and hail will be
the primary threats.

....Upper Mississippi Valley/Western Great Lakes...
A subtle mid-level shortwave trough is forecast to move eastward
into the upper Mississippi Valley on Monday afternoon. To the east
of the trough, moderate to strong instability is forecast to develop
from central Iowa eastward into northern Illinois. The greatest
convective coverage is expected to develop further to the north
across parts of Wisconsin, where instability will be weaker but
deep-layer shear will be greater. The combination of instability and
deep-layer shear across Wisconsin could be sufficient for a marginal
wind-damage threat during the late afternoon and early evening. This
threat, along with a potential for hail could extend southwestward
into central Iowa where strong instability is forecast.

...Broyles.. 08/17/2025

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