Storm Prediction Center Mesoscale Discussion 1229

   Mesoscale Discussion 1229
   NWS Storm Prediction Center Norman OK
   1251 PM CDT Sun Jun 21 2026

   Areas affected...Western Nebraska...northeast Colorado...and
   northwest Kansas

   Concerning...Severe potential...Watch likely 

   Valid 211751Z - 211945Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Conditions are being monitored for thunderstorm initiation
   across the NE/CO/KS tri-state region, which may be within the next
   1-2 hours. Watch issuance is likely at some point this afternoon.

   DISCUSSION...Latest GOES imagery and surface observations show the
   early stages of deepening cumulus in proximity to a diffuse surface
   low and along low-level trough axes/confluence zones. This comes as
   upper-level ascent associated with an upstream wave over WY
   continues to migrate southeast and as temperatures begin to warm
   into the upper 70s and low 80s. Recent RAP mesoanalyses continue to
   show some lingering inhibition across the effective warm sector
   (where dewpoints remain the 50s to low 60s), but forecast guidance
   suggests that this inhibition will be largely removed as
   temperatures continue to warm into the low to mid 80s. 

   These solutions also depict initiation of deep convection by around
   20 UTC; however, based on the latest GOES trends and current
   temperatures, initiation may occur slightly earlier across western
   NE and along the NE/CO border. Once initiation does occur,
   convection will mature within an environment favorable for splitting
   supercells capable of very large hail given mostly straight,
   elongated hodographs across the region and sufficient mixed-layer
   buoyancy (MLCAPE of around 1500-2000 J/kg). Consequently, watch
   issuance is expected in the coming hours as initiation becomes more
   probable.

   ..Moore/Hart.. 06/21/2026

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

   ATTN...WFO...LBF...GLD...BOU...CYS...

   LAT...LON   42060288 42400254 42560212 42510158 42230122 41870097
               41010074 40310062 39760062 39320073 39120096 38900134
               38930181 39090223 39430251 39780266 40440285 41010291
               41700300 42060288 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN