ACUS11 KWNS 042043 SWOMCD SPC MCD 042042 OHZ000-MIZ000-INZ000-ILZ000-WIZ000-IAZ000-042245- Mesoscale Discussion 0638 NWS Storm Prediction Center Norman OK 0342 PM CDT Mon May 04 2026 Areas affected...portions of the Midwest and southern Great Lakes Concerning...Severe potential...Watch possible Valid 042042Z - 042245Z Probability of Watch Issuance...40 percent SUMMARY...Widely scattered to scattered thunderstorm development is expected late this afternoon, with potential for severe/damaging wind gusts and large hail. Watch issuance is possible for a portion of the discussion area. DISCUSSION...Prevailing southwesterly flow has yielded modest moisture return across portions of the Midwest into the southern Great Lakes region, with dewpoints climbing into the 40s/low-50s. While a surface cold front remains displaced to the northwest, expectation is for widely scattered to scattered strong to severe thunderstorms to develop within the warm conveyor this afternoon as convective temperatures are reached and remaining inhibition is removed. A 700-mb speed max associated with an approaching shortwave trough will help to promote 30-40 kts of effective bulk shear across the region, with MLCAPE forecast in the 500-1250 J/kg range. This will be sufficient to support storm organization into multicells/clusters and perhaps transient supercell structures; although, the lack stronger flow aloft and limited hodograph elongation is likely to limit supercell intensity/persistence. Dry mid-level air and well-mixed boundary layers (as sampled by regional ACARS profiles and the 18z DVN observed sounding) will support a risk for severe/damaging wind gusts. Large hail will also be possible given modestly steep mid-level lapse rates (>7 C/km per latest mesoanalysis). While a strengthening of 850 mb flow and some accompanying increase in low-level hodograph curvature is expected this evening (especially across northern Indiana and northwest Ohio within the 21-00z time frame), the tornado threat remains uncertain owing to the expectation for boundary layer moisture quality to remain more limited across the region. Thus, given the potential for these hazards, a Severe Thunderstorm Watch is possible for a portion of the discussion area, particularly from northeastern Illinois into northwestern Ohio where the potential coverage of severe hazards appears greater. ..Chalmers/Smith.. 05/04/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND...LOT...ILX... MKX...DVN... LAT...LON 40518958 40679037 41009087 41529106 42019081 42459004 42658882 42808808 42928668 42858577 42578475 42178393 41858341 41368312 40998314 40728341 40518462 40438591 40448725 40458834 40478912 40518958 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN