Mesoscale Discussion 1249
   NWS Storm Prediction Center Norman OK
   0202 PM CDT Thu Jun 13 2024

   Areas affected...Northwest/West-Central IL...Southern IA...Northern
   MO...Far Southeast NE...Northeast KS

   Concerning...Severe potential...Watch likely 

   Valid 131902Z - 132100Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Severe thunderstorms are expected to develop along and
   ahead of a cold front from northwest/west-central Illinois into far
   southeast Nebraska and northeast Kansas this afternoon. Very large
   hail up to 3" in diameter and gusts from 60 to 80 mph are possible
   and a watch will be needed to cover this severe potential.

   DISCUSSION...Recent visible satellite imagery has recently shown an
   increase in deepening cumulus along a pre-frontal trough from
   northwest/west-central IL west-southwestward into far southeast NE
   and northeast KS. Temperatures in this region have warmed into the
   upper 80s/low 90s amid dewpoints in the low 70s, contributing to
   very strong buoyancy. Recent mesoanalysis estimates MLCAPE currently
   ranges from 2500 J/kg over IL to over 3500 J/kg across far southeast
   NE and northeast KS. These values will likely increase as strong
   diurnal heating persists throughout the afternoon. As observed in
   recent ACARS soundings and the 18Z DVN sounding, some convective
   inhibition remains in place, but continued diurnal heating should
   help to erode this inhibition as well. 

   Robust thunderstorm development is expected to take place quickly
   once inhibition erodes and convective initiation occurs. Large to
   very large hail up to 3" in diameter is possible with the initial,
   more cellular development. Strong buoyancy amid high cloud bases and
   steep low-level lapse rates will foster strong outflow, with the
   potential for this outflow to amalgamate with resultant upscale
   growth into a coherent convective line. When this occurs, the
   primary severe risk should shift to severe gusts (i.e. 60 to 80
   mph). Veered low-level flow and a mixed boundary layer should
   mitigate the tornado potential, although a low probability for a
   tornado or two exists whenever there is a predominantly
   supercellular mode.

   ..Mosier/Gleason.. 06/13/2024

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

   ATTN...WFO...ILX...LSX...DVN...DMX...EAX...OAX...TOP...

   LAT...LON   41828982 41308948 40268979 39839035 39449156 38959420
               39019582 40349654 41159471 41469241 41899111 41828982