Storm Prediction Center Mesoscale Discussion 1684

   Mesoscale Discussion 1684
   NWS Storm Prediction Center Norman OK
   0907 PM CDT Mon Jul 20 2026

   Areas affected...central Iowa

   Concerning...Tornado Watch 500...

   Valid 210207Z - 210330Z

   The severe weather threat for Tornado Watch 500 continues.

   SUMMARY...The damaging wind risk may persist beyond the scheduled
   03Z watch expiration. A new severe thunderstorm watch is possible.

   DISCUSSION...A cold-pool-driven storm complex was located over Des
   Moines as of 0155Z with KDMX base velocities indicating outbound
   values in excess of 50 kt on the south side of the metropolitan
   area. Environmentally, low-level lapse rates are gradually weakening
   with no indication of a rear-inflow jet in the KDMX VWP.
   Nonetheless, the presence of seasonably strong vertical shear and
   residual moderate instability, per latest objective analysis,
   suggests that the risk for damaging winds may persist beyond the
   scheduled 03Z expiration of the watch. As such, convective trends
   are being monitored for the possibility of a new severe thunderstorm
   watch or a local extension of the existing watch.

   ..Mead.. 07/21/2026

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

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

   LAT...LON   40619305 41239371 41809406 41959369 41469234 40789211
               40619228 40619305 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN