Storm Prediction Center Mesoscale Discussion 859

   Mesoscale Discussion 0859
   NWS Storm Prediction Center Norman OK
   0212 PM CDT Sun May 18 2025

   Areas affected...northeast Colorado...western Nebraska...northwest
   Kansas

   Concerning...Severe potential...Watch likely 

   Valid 181912Z - 182145Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Supercells capable of very large hail, tornadoes, and
   damaging wind are likely to develop after 21Z over northeast
   Colorado, spreading into western Nebraska and northwest Kansas
   through evening.

   DISCUSSION...A surface low continues to deepen over eastern CO as
   the shortwave trough moves across the area. Surface analysis shows a
   prominent plume of low-level moisture extending out of western KS
   and across northeast CO, where dewpoints are holding in the lower
   50s F. 

   Full heating near and south of this moisture plume will erode the
   minimal capping inversion by around 21Z, and rapid thunderstorm
   development is expected. The combination of strong instability,
   steep lapse rates, and veering winds with height will strongly favor
   supercells capable of very large hail, and a few tornadoes. Activity
   should easily remain severe into NE and KS this evening as the
   southeasterly low-level jet persists, maintaining moisture advection
   as well as shear and inflow.

   ..Jewell/Hart.. 05/18/2025

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

   ATTN...WFO...GID...LBF...DDC...GLD...PUB...BOU...CYS...

   LAT...LON   39239981 38670057 38350123 38330167 38340215 39110277
               39420328 39670364 39890412 40260434 40540451 40870437
               41320401 41530379 41700344 41680291 41470190 41060094
               40019974 39689971 39239981 

   MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN