Mesoscale Discussion 1338
   NWS Storm Prediction Center Norman OK
   1240 PM CDT Thu Jun 29 2023

   Areas affected...CO Front Range and adjacent high plains...southeast
   and eastern WY...western NE Panhandle

   Concerning...Severe potential...Tornado Watch likely 

   Valid 291740Z - 291945Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Convective initiation will occur over the Medicine
   Bow/Laramie Ranges by 12pm MDT, and the Front Range by 1-2pm MDT. 
   Discrete supercells are forecast to develop later this afternoon
   once updrafts mature/intensify.  A couple of tornadoes are possible,
   including very large hail (diameters 2-3 inches).

   DISCUSSION...Visible satellite imagery shows developing convection
   over the Medicine Bow Range with a building cumulus field located
   near the Continental Divide west of Denver.  The airmass is very
   moist with mid 50s surface dewpoints prevalent from the Palmer
   Divide northward through Cheyenne and into northeast WY.  Strong
   heating will continue to occur through mid-late afternoon as
   temperatures warm through the 70s.  Forecast soundings indicate
   convective inhibition is minimal as temperatures warm into the
   mid-upper 70s.  Very steep lapse rates are denoted on the forecast
   soundings (around 8 deg C/km in the surface to 300 mb layer).

   The moist low-level upslope flow coupled with orographic lift
   downstream of a mid-level trough pivoting eastward through the
   eastern Great Basin, will promote scattered thunderstorms developing
   by mid afternoon from near I-70 northward along I-25 into eastern
   WY.  Moderate buoyancy (2000-2500 J/kg MLCAPE) and long hodographs
   will favor discrete supercells initially with the more intense
   storms.  Large to very large hail is becoming increasingly probable
   this afternoon both in the general Denver vicinity and near/north of
   the Cheyenne Ridge per CAM model guidance.  The moist low levels
   coupled with a supercellular mode lend the possibility for
   tornadoes.  As storms move into the western NE Panhandle and far
   northeast CO during the early evening, expecting storm outflows to
   promote some clustering into a potential MCS.

   ..Smith/Guyer.. 06/29/2023

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

   ATTN...WFO...UNR...BOU...CYS...

   LAT...LON   39510525 41030568 41500616 42670600 43240558 43400486
               42940385 41170365 39730377 39270433 39270494 39510525