ACUS11 KWNS 181853

SWOMCD

SPC MCD 181852 

WIZ000-IAZ000-MNZ000-182045-



Mesoscale Discussion 2024

NWS Storm Prediction Center Norman OK

0152 PM CDT Tue Aug 18 2026



Areas affected...Northern Iowa into southeast Minnesota and

southwestern Wisconsin



Concerning...Severe potential...Watch likely 



Valid 181852Z - 182045Z



Probability of Watch Issuance...80 percent



SUMMARY...Large hail (some around 2 in.) and damaging winds will be

possible with scattered storms in the Upper Midwest. A watch is

likely this afternoon.



DISCUSSION...A weak MCV and associated cloud cover is present within

much of central/southern Wisconsin this afternoon. That said, strong

heating is occurring near a surface trough in northeast Iowa.

Thunderstorms have recently developed but have thus far not been

able to mature. Continued destabilization into southwestern

Wisconsin may allow this activity to pose an increasing severe

threat over the next couple of hours. Convective coverage is also

expected to increase along the cold front, though this may be

delayed until later this afternoon given the cloud cover. Moderately

strong mid-level winds on the southern flank of the upper-level low

is supporting around 40-45 kt of effective shear. Hodographs are

long and straight which suggests splitting supercells. Large hail

(with hail to around 2 inches possible, particularly in the

westernmost areas where mid-level lapse rates are steeper) and

damaging winds will be possible this afternoon.



..Wendt/Guyer.. 08/18/2026



...Please see www.spc.noaa.gov for graphic product...



ATTN...WFO...GRB...MKX...DVN...ARX...MPX...DMX...



LAT...LON   42579070 42349238 42389302 42499334 43029352 43669364

            44319313 44689080 44338997 43978961 42968992 42579070 



MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH

MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN