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