Storm Prediction Center Mesoscale Discussion 465

   Mesoscale Discussion 0465
   NWS Storm Prediction Center Norman OK
   1242 AM CDT Fri Apr 18 2025

   Areas affected...Northern Iowa

   Concerning...Severe potential...Watch unlikely 

   Valid 180542Z - 180815Z

   Probability of Watch Issuance...20 percent

   SUMMARY...A threat for marginally severe hail is expected over the
   next few hours across northern Iowa. Weather watch issuance appears
   unlikely.

   DISCUSSION...The latest water vapor imagery shows west to southwest
   flow over the Upper Midwest, with some anticyclonic curvature. In
   spite of some ridging, the RAP suggests a minor shortwave trough is
   moving through Iowa. At the surface, a front extends northeastward
   across central Iowa. Scattered thunderstorms are ongoing to the
   northwest of the front in the vicinity of Sioux City, Iowa. RAP
   forecast soundings to the north of front over much of northern Iowa
   have an inversion up to near 800 mb. MUCAPE is up to 1500 J/kg with
   effective shear in the 50 to 60 knots range. 700-500 mb lapse rates
   are near 8 C/km. As warm advection continues overnight, this
   environment should support elevated supercell development.
   Supercells may be able to produce isolated large hail, but any
   threat is expected to remain isolated.

   ..Broyles/Gleason.. 04/18/2025

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

   ATTN...WFO...DVN...ARX...DMX...FSD...OAX...

   LAT...LON   42289246 42249433 42179531 42229595 42539635 42729641
               42889639 43239600 43429526 43449260 43179150 42459149
               42289246 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN