Milwaukee, WI...Madison, WI...Sioux Falls, SD...Green Bay, WI...Duluth, MN...
Probabilistic Damaging Wind Graphic
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.
Milwaukee, WI...Madison, WI...Rockford, IL...Sioux Falls, SD...Cedar Rapids, IA...
SPC AC 181622
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Sat Jul 18 2020
Valid 181630Z - 191200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER PARTS OF MINNESOTA AND WISCONSIN...
...SUMMARY...
Damaging thunderstorm gusts, large hail and isolated tornadoes are
possible this afternoon and tonight across portions of the Upper
Midwest and Upper Great Lakes States.
...Upper Midwest...
Latest surface analysis shows a cold front extending from northern
MN southward into western SD. A weak low along the front will be
over southwest MN later this afternoon, enhancing convergence and
leading to scattered thunderstorm development. Visible satellite
imagery shows clear skies in this region, with southerly low-level
winds helping to return 70s dewpoints to the area. Forecast
soundings across southern/central MN into western WI show a very
unstable air mass later today with MLCAPE values of 5000+ J/kg.
Rapid thunderstorm development is expected in the 20-23z period,
with sufficient deep-layer vertical shear to support a few
supercells capable of very large hail. Low-level flow/shear is not
particularly strong, but the degree of instability and proximity to
surface boundaries could result in a tornado or two as well.
Activity is likely to congeal into an MCS as it tracks eastward into
western WI this evening.
An ENG risk area has been added to the region with highest
confidence of storm coverage/severity. However, various model
solutions suggest some potential that the area of concern could grow
southeastward this evening into more of southeast MN and central WI.
This will be re-evaluated in later outlook updates.
...Carolinas...
Similar to yesterday scattered and relatively disorganized
thunderstorms are expected to form over parts of NC, with slow
development southeastward into SC. The strongest cells may
occasionally produce gusty winds.
..Hart/Moore.. 07/18/2020
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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