Storm Prediction Center Mesoscale Discussion 777

   Mesoscale Discussion 0777
   NWS Storm Prediction Center Norman OK
   0329 PM CDT Mon May 18 2026

   Areas affected...Portions of Mid-Missouri Valley Region

   Concerning...Severe potential...Watch likely 

   Valid 182029Z - 182230Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The threat for severe storms will increase into the
   evening. Tornadoes will remain possible along the Iowa/Missouri
   border with hail becoming the primary hazard with northward extent.
   One or more watches will be needed this afternoon.

   DISCUSSION...At least modest airmass recovery has occurred along the
   Iowa/Missouri border region. Dewpoints have risen into the mid 60s
   to low 70s F in some locations. North of the boundary, steep
   mid-level lapse rates are in place per the 18Z OAX sounding. As the
   shortwave trough moves into the area, additional storm development
   is likely. This is already occurring in eastern Nebraska.
   Furthermore, additional theta-e advection ahead of the ongoing
   supercells in north-central Kansas and southeast Nebraska will allow
   a tornado threat to persist northeast of PDS WW 222. One or more
   watches will be needed this afternoon. The tornado threat will be
   maximized south of the boundary with a transition to more of a hail
   threat with elevated storms to the north.

   ..Wendt/Hart.. 05/18/2026

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

   ATTN...WFO...DMX...EAX...OAX...TOP...GID...

   LAT...LON   40569724 41199752 41659722 41989617 41969535 41769429
               41399360 40759341 40029371 39529415 39589472 39809501
               40569724 

   MOST PROBABLE PEAK TORNADO INTENSITY...140-170 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN