Storm Prediction Center Mesoscale Discussion 766

   Mesoscale Discussion 0766
   NWS Storm Prediction Center Norman OK
   1032 PM CDT Sun May 17 2026

   Areas affected...northeast Iowa into southwest Wisconsin

   Concerning...Tornado Watch 216...218...

   Valid 180332Z - 180530Z

   The severe weather threat for Tornado Watch 216, 218 continues.

   SUMMARY...Potential remains for damaging winds with the main line of
   storms. A brief tornado cannot be ruled out.

   DISCUSSION...A bow-echo is currently moving across north-central IA,
   with much of the push now north of the warm front. Recent surface
   observations indicate weaker wind gusts compared to earlier this
   evening as the cooler air is encountered.

   A warm front currently exists from this bow eastward into far
   southern WI. This boundary has not moved much, but may retreat
   northward overnight allow further destabilization into northeast IA
   and southwest WI. 

   Given the 50 kt low-level jet, the surface cool layer immediately
   north of the warm front may become shallow enough to allow severe
   gusts to the surface. As such, the severe wind risk is expected to
   persist with the existing bow, and perhaps with additional waves
   that may form farther south along the squall line entering into
   central IA. An additional watch and/or extension may be needed into
   the remainder of eastern IA and into southwest WI in the coming
   hours.

   ..Jewell.. 05/18/2026

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

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

   LAT...LON   41919421 42309364 42969324 43259330 43469340 43719375
               43889314 43919217 43809118 43569063 43269036 42859044
               42499094 42259153 41919421 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN