Storm Prediction Center Mesoscale Discussion 1364

   Mesoscale Discussion 1364
   NWS Storm Prediction Center Norman OK
   0458 PM CDT Fri Jun 21 2024

   Areas affected...Parts of northern IA and southern MN

   Concerning...Severe Thunderstorm Watch 445...

   Valid 212158Z - 212330Z

   The severe weather threat for Severe Thunderstorm Watch 445
   continues.

   SUMMARY...Trends are being monitored for possible downstream watch
   issuance in northern Iowa and perhaps far southern Minnesota. At
   least isolated severe hail/damaging winds and a couple tornadoes all
   appear possible.

   DISCUSSION...A supercell which has recently exhibited some low-level
   rotation is ongoing across northwest IA, generally along/near a
   surface front. Other strong to severe convection is ongoing farther
   east across northern IA along this boundary. This activity is likely
   being aided by modest warm advection associated with a weak
   southwesterly low-level jet over the central Plains and mid MO
   Valley. Although mid-level flow is not overly strong per recent
   mesoanalysis estimates, sufficient veering/strengthening of the
   winds through mid levels (in recent VWPs from KFSD) is supporting
   around 30-45 kt of deep-layer shear. A mix of multicells and
   supercells will remain possible as convection spreads slowly
   eastward along/near the front across northern IA over the next
   several hours. At least isolated severe hail around 1-2 inches in
   diameter and damaging winds generally 55-70 mph should be the main
   threats with this activity in the short term. The threat for severe
   winds may increase this evening if a small bowing cluster can
   consolidate along the front. Low-level shear/winds remain somewhat
   weak at the moment, but a couple of tornadoes may still occur with
   any sustained, surface-based supercell. Observational trends will be
   closely monitored for possible downstream watch issuance into
   northern IA and vicinity.

   ..Gleason/Edwards.. 06/21/2024

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

   ATTN...WFO...ARX...MPX...DMX...FSD...

   LAT...LON   43319573 43669546 43869466 43889257 43869166 43539129
               43009136 42869244 42569401 42389497 42579543 43319573