Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
SPC AC 290104
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0804 PM CDT Wed Jul 28 2021
Valid 290100Z - 291200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER A PORTION
OF THE UPPER MIDWEST AND GREAT LAKES REGION...
Widespread severe storms with occasional significant severe wind
damage are expected this evening into tonight along a corridor from
northeastern Minnesota across Wisconsin to southwest Lower Michigan.
...Upper Midwest and Great Lakes region...
As of early evening, robust surface-based thunderstorm initiation is
underway in several areas across the Upper Midwest including along a
cold front over northeast MN as well as along a pre-frontal boundary
across northwest WI. Storms are expected to increase in coverage
this evening over northern WI in response to an strengthening
southwesterly low-level jet coupled with a low-amplitude shortwave
trough moving southeast along the northern periphery of an upper
ridge. Some of the initial storms may exhibit supercell
characteristics given 45+ kt effective bulk shear and 3000+ J/kg
MLCAPE. Very large hail and isolated tornadoes are possible mainly
through mid-evening. However, storms should eventually congeal into
a forward-propagating MCS with line/bowing segments and spread
southeast along the instability gradient. Widespread damaging wind
(some significant) and possibly a few QLCS tornadoes should become
the main threats later this evening into the overnight.
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z