Storm Prediction Center Mesoscale Discussion 1680

   Mesoscale Discussion 1680
   NWS Storm Prediction Center Norman OK
   0635 PM CDT Mon Jul 20 2026

   Areas affected...central Iowa

   Concerning...Tornado Watch 500...

   Valid 202335Z - 210100Z

   The severe weather threat for Tornado Watch 500 continues.

   SUMMARY...A focused corridor of damaging wind potential may be
   evolving near or just east of the Des Moines vicinity through 01Z.
   Large to very large hail is also possible.

   DISCUSSION...Latest trends in volumetric radar data indicate
   multiple supercells near Ames with some signal that a
   larger-than-RFD-scale cold pool may be evolving. An outflow boundary
   precedes those storms with that feature moving southwest at around
   10 kt. Current thinking is that continued storm mergers may support
   the evolution of another bow echo configuration, which would track
   to the south-southeast along the immediate cool side of the leading
   outflow boundary, near or just to the east of the Des Moines metro
   area. Should that scenario unfold, corridor of strong winds with
   gusts of 65-75 mph are possible. To the immediate west/northwest,
   additional supercell structures may continue to backbuild, near the
   intersection of the east-west front and north-south outflow
   boundary. Large to very large hail will remain possible in that
   regime, as well as the potential for a tornado or two.

   ..Mead.. 07/20/2026

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

   ATTN...WFO...DVN...DMX...

   LAT...LON   41369318 41769365 42159386 42299323 41539249 41229236
               41149263 41129287 41369318 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN