Storm Prediction Center Mesoscale Discussion 1478

   Mesoscale Discussion 1478
   NWS Storm Prediction Center Norman OK
   0507 PM CDT Fri Jun 27 2025

   Areas affected...portions of northwest and north-central South
   Dakota

   Concerning...Severe potential...Watch possible 

   Valid 272207Z - 272330Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Initial high-based convection across northeast WY may
   persist and intensify across northwest SD this afternoon/evening.
   Confidence in storm evolution is low, but a mix of supercells and
   clusters could support a hail and wind risk. Conditions are being
   monitored for possible WW issuance.

   DISCUSSION...As of 22 UTC, regional observations showed a complex
   surface pattern evolving across the central and northern High
   Plains. Several thunderstorms have initiated along a wind shift
   across the higher terrain of northeastern WY as ascent from a
   mid-level shortwave trough has moved overhead. While initially
   high-based, these storms are approaching the western edge of a very
   unstable warm sector with deep surface moisture concentrated along
   the northern periphery of the Black Hills. Moderate vertical shear
   is also present from the UDX VAD sufficient for supercells.

   Recent CAM guidance and observational trends suggest these storms
   may continue to intensify as they move eastward. However, there
   remains considerable uncertainty on the converge of the stronger
   storms. The large buoyancy and supportive shear would favor a risk
   for large to very large hail and damaging gusts. The presence of
   multiple surface boundaries could also support a brief tornado with
   any of the stronger rotating storms. Given the increasing severe
   potential, convective trends will continue to be monitored for WW
   issuance across parts of northwest and north-central SD.

   ..Lyons/Guyer.. 06/27/2025

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

   ATTN...WFO...ABR...UNR...BYZ...

   LAT...LON   44190288 44310121 45140057 45920066 45920382 45240406
               44620386 44190299 44190288 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.75-4.25 IN