ACUS11 KWNS 201853
SWOMCD
SPC MCD 201853
MIZ000-WIZ000-IAZ000-MNZ000-202100-

Mesoscale Discussion 1674
NWS Storm Prediction Center Norman OK
0153 PM CDT Mon Jul 20 2026

Areas affected...Northeast Iowa into northwest/north-central
Wisconsin

Concerning...Severe potential...Tornado Watch likely

Valid 201853Z - 202100Z

Probability of Watch Issuance...95 percent

SUMMARY...All severe hazards, including some significant, are
possible as supercells develop by late afternoon. Timing and
location of initiation are the main uncertainties. A tornado watch
is likely.

DISCUSSION...A very moist airmass is evident ahead of a cold front
in the Upper Mississippi Valley. A capping inversion was present on
the 12Z MPX observed sounding. Cumulus along the front have yet to
become vertically developed as a result. Mid-level convection has
been ongoing in southern Minnesota. This activity is now moving into
modifying outflow from an earlier MCS in the La Crosse/Davenport
vicinity. Lift from a shortwave trough in northern Minnesota will
continue to overspread the area this afternoon. With time, continued
heating and moistening ahead of the cold front and near the outflow
front intersection should allow storms to develop, most likely by
late afternoon. Given strong shear (50-60 kt effective) across the
cold front, supercell structures will be favored. Steep mid-level
lapse rates will support the threat for large to very-large hail. A
tornado threat, some possibly strong, will also be present with
supercells. Severe winds will also be possible. Wind gusts of 75+
mph are possible, particularly where activity grows upscale. The
exact timing/location of storm initiation is not clear though a
tornado watch is likely.

..Wendt/Thompson.. 07/20/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!5ExASKsIu-mhSCWas8flx3VOb25FJAWX0OpKbJ7KU6AeeIvisJLdbH8FyDnlR6pTPmA_ogtuTTsf9xtw38rs2WlDeo8$ for graphic product...

ATTN...WFO...MQT...GRB...MKX...DLH...ARX...MPX...

LAT...LON 43609277 44549244 46519079 46729022 46408897 45168894
43798985 43379033 43099126 43079238 43609277

MOST PROBABLE PEAK TORNADO INTENSITY...120-145 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


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* Origin: capitolcityonline.net * KY, USA (1:2320/107)