ACUS11 KWNS 181341
SWOMCD
SPC MCD 181340 
INZ000-ILZ000-MOZ000-181545-

Mesoscale Discussion 0769
NWS Storm Prediction Center Norman OK
0840 AM CDT Mon May 18 2026

Areas affected...Central Illinois into western Indiana

Concerning...Severe potential...Watch possible 

Valid 181340Z - 181545Z

Probability of Watch Issuance...40 percent

SUMMARY...Damaging wind potential will probably increase in parts of
central Illinois/western Indiana. Depending on convective trends, a
watch may be need. Timing is uncertain, however.

DISCUSSION...South of a weak outflow boundary, a line of convection
continues eastward this morning. Trends from CAPPI data suggest
occasional intensification of updrafts. Upper 60s F dewpoints are
noted in southern Illinois and will be advecting northward ahead of
this activity. Surface observations also indicate relatively strong
pressure rises behind the line. With filtered surface heating
occurring in central Illinois, the main question with this
convection will be how intense it will become and when that
intensification will occur. The threat for damaging winds will
probably increase over the next few hours. A watch is possible
depending on convective trends.

..Wendt/Hart.. 05/18/2026

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

ATTN...WFO...IWX...IND...LOT...ILX...LSX...DVN...

LAT...LON   38978956 38879015 38899065 39049065 39639043 40329022
            40859008 41038970 41638776 41538679 40608665 39698691
            39248824 38978956 

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN