Storm Prediction Center Mesoscale Discussion 854

   Mesoscale Discussion 0854
   NWS Storm Prediction Center Norman OK
   0347 PM CDT Mon May 20 2024

   Areas affected...Northeast Colorado...southeast Wyoming...southwest
   Nebraska

   Concerning...Severe potential...Watch possible 

   Valid 202047Z - 202315Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Initially high-based convection within the Front Range
   into southeast Wyoming will eventually spread east and intensify.
   Primary hazards will be severe wind gusts and large/very-large hail.
   A mesoscale corridor with greater tornado risk will in northeast
   Colorado and vicinity within the moisture axis. A watch will
   eventually be needed this afternoon.

   DISCUSSION...Convection continues to develop along the Front Range
   as upslope flow continues this afternoon. A weak thunderstorm has
   formed recently south of Denver in drier air. The exact timing of
   storm greater initiation/intensification is a bit unclear, but the
   approach of the mid-level ascent from the Four Corners region should
   foster additional development within the next 2-3 hours or so.
   Further, the lee trough to the east should also deepen and pull
   richer surface moisture (upper 50s to low 60s F, as observed in
   upstream in Kansas) into northeast Colorado and southwest Nebraska.
   The current thinking is that storms will initiate within the Front
   Range as well as southeast Wyoming. Storms will initially be
   high-based and primarily capable of severe wind gusts and large
   hail. Storm intensification can be expected as they encounter richer
   moisture to the east. A greater tornado threat will exist with
   supercells moving within the moisture axis in northeast Colorado and
   nearby vicinity. Here, backed surface winds will combine with an
   eventual modest increase in easterly 850 mb winds to increase
   low-level hodograph curvature. Very-large hail will also become more
   probable as supercell storms intensify farther east.

   ..Wendt/Hart.. 05/20/2024

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

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

   LAT...LON   39750224 39500376 40130466 41140504 41630438 41680241
               41230173 40350176 39750224