Storm Prediction Center Mesoscale Discussion 878

   Mesoscale Discussion 0878
   NWS Storm Prediction Center Norman OK
   0503 PM CDT Tue May 21 2024

   Areas affected...Central Iowa and far southeastern Minnesota

   Concerning...Tornado Watch 277...

   Valid 212203Z - 212330Z

   The severe weather threat for Tornado Watch 277 continues.

   SUMMARY...Long tracked supercells within a line extending north to
   south across central IA will continue to move eastward into an even
   more favorable tornadic environment.

   DISCUSSION...Ongoing tornadic supercells continue from Cambridge, to
   just east of Des Moines. The latest DMX VAD profile data indicates
   0-1 km SRH around 100 m2/s2. However, just upstream the DVN VAD
   shows SRH is double to triple that. In addition, a corridor of
   higher boundary layer moisture and backed surface flow east of the
   current line of deep moist convection from around Olmsted County
   south-southeastward to Linn County suggests localized SRH should be
   maximized there, juxtaposed with maximum buoyancy. Therefore, the
   potential for long tracked, damaging tornadoes appears most likely
   over the next 1-2 hours as far north as extreme southeastern MN.

   ..Barnes.. 05/21/2024

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

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

   LAT...LON   40659371 41099392 42139384 42969359 43329321 44129282
               44109237 43739184 43349151 42809142 42109155 41769160
               41149196 40749235 40599255 40659371