Storm Prediction Center Mesoscale Discussion 2317

   Mesoscale Discussion 2317
   NWS Storm Prediction Center Norman OK
   0612 PM CDT Sun Sep 20 2026

   Areas affected...portions of eastern/southeastern Colorado and
   extreme west-central Kansas

   Concerning...Severe Thunderstorm Watch 673...

   Valid 202312Z - 210045Z

   The severe weather threat for Severe Thunderstorm Watch 673
   continues.

   SUMMARY...Damaging hail will be possible for the next 1-2 hours.
   Additional thunderstorms capable of large hail are possible this
   evening.

   DISCUSSION...A mature supercell continues to track southeast across
   the Plains of eastern Colorado this afternoon. This supercell has a
   history of producing very large hail (in excess of 2.5"). The
   environment along and ahead of this supercell remains conducive for
   maintaining its current intensity given effective-layer shear around
   45 knots and MUCAPE between 1500-2000 J/kg. Absent the development
   of additional thunderstorms that may destructively interfere, the
   current supercell should continue to pose a threat for
   large-to-very-large hail over the next couple of hours, with overall
   magnitude of the hail size governed by storm-scale processes. 

   With time this afternoon and into the evening, the expectation is
   that the boundary layer will cool sufficiently with the loss of
   diurnal heating that a gradual weakening of the supercell should
   commence. As such, the overall magnitude of any potential hail
   should wane as well. 

   Additional thunderstorms capable of large hail and damaging winds
   are still possible behind this initial supercell and that potential
   will continue to be monitored.

   ..Marsh.. 09/20/2026

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

   ATTN...WFO...DDC...GLD...PUB...BOU...

   LAT...LON   38810318 39080296 39060248 38880221 38630199 38240191
               38040205 38020250 38280291 38640309 38810318 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN