525
ACUS11 KWNS 171804
SWOMCD
SPC MCD 171803
ILZ000-MOZ000-IAZ000-KSZ000-172000-
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
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