Storm Prediction Center Mesoscale Discussion 1165

   Mesoscale Discussion 1165
   NWS Storm Prediction Center Norman OK
   0103 PM CDT Wed Jun 17 2026

   Areas affected...portions of northern/central Missouri...western
   Illinois

   Concerning...Severe potential...Watch likely 

   Valid 171803Z - 172000Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Thunderstorm development likely by the afternoon with
   potential for all hazards including damaging wind, large hail, and
   strong tornadoes.

   DISCUSSION...Morning convection has moved into central/eastern
   Illinois, with trailing outflow and a zone of differential heating
   extending across northern Missouri into south-central Illinois. This
   zone will be the focus of redevelopment of thunderstorm activity
   this afternoon. Strong daytime heating is ongoing across
   central/northern Missouri into far western Illinois in the cloud
   free zone south of the outflow. SPC Mesoanalysis indicates that
   MLCIN is eroding in this region, with temperatures climbing into the
   mid 80s F. This is further confirmed by visible satellite trends
   with the cumulus near the vicinity of the outflow also becoming
   increasingly agitated.

   Strong deep layer shear around 50-55 kts is analyzed across this
   region, with STP around 2-3 across northern Missouri into far
   western Illinois. This in combination with strong to moderate
   instability edging northward will likely support initial supercells
   capable of large hail, damaging wind, and tornadoes (perhaps
   strong). A 40-50 kt low level jet axis extends from the
   southern/central Plains into Missouri/western Illinois. This is
   progged to shift north and eastward through the afternoon, which may
   shift the higher STP and more favorable tornado potential into
   portions of western/central Illinois.

   One or more watches will likely be needed to cover this potential
   this afternoon.

   ..Thornton/Hart.. 06/17/2026

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

   ATTN...WFO...LOT...ILX...LSX...DVN...SGF...EAX...TOP...

   LAT...LON   38788965 39578844 40158794 40518805 40738844 40788904
               40599090 40469164 40309251 40129360 40049405 39629469
               39309489 38959516 38169511 37979368 38499057 38619015
               38788965 

   MOST PROBABLE PEAK TORNADO INTENSITY...140-170 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN