ZCZC SPCSWOMCD ALL ACUS11 KWNS 250031 SPC MCD 250031 OHZ000-MIZ000-INZ000-ILZ000-250230- Mesoscale Discussion 1344 NWS Storm Prediction Center Norman OK 0731 PM CDT Sat Jul 24 2021 Areas affected...portions of southern Lower MI...western Lake Erie...northwestern OH...northern IN...and northern/central IL. Concerning...Severe Thunderstorm Watch 390...391... Valid 250031Z - 250230Z The severe weather threat for Severe Thunderstorm Watch 390, 391 continues. SUMMARY...Bands of thunderstorms will continue to offer a threat for damaging gusts from central/northeastern IL to southern MI, and a pocket of additional tornado potential exists in the southeastern Lower MI area. Another watch may be required in a narrow corridor southeast of the existing watches over portions of northwestern OH and/or central/northeastern IN. DISCUSSION...The most intense band of convection continues to be the activity moving southeastward at an erratic/25-35-kt pace across southeastern Lower MI. In addition to damaging gusts, a couple tornadoes appear to have occurred in the last hour, within short- lived but intense embedded mesocyclones. This potential will continue for another hour or two as the convection encounters a pocket of relatively high-SRH air (effective SRH 150-350 J/kg), based on radar imagery, VWP analysis and objective mesoanalysis data. Low-level shear decreases with southwestward extent over IN and central IL where surface winds are more veered, generally in step with an increase in buoyancy (as represented by a westward- broadening, prefrontal corridor of MLCAPE in the 2000-3000 J/kg range). Still, given the available moisture and depth of the buoyant layer, water-loaded downdrafts still will be capable of localized damaging to severe gusts. Theta-e and buoyancy will continue to diminish with southeastward extent over western OH and eastern IN, but activity may continue at or near severe levels past the current versions of both watches (in space and time). Additional local extensions or a narrow new watch could be needed to cover this potential into the evening. ..Edwards.. 07/25/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND...LOT...ILX... LAT...LON 40478983 40598861 41048714 41468576 41958541 42568333 42418299 41918312 41568298 40658465 40158715 40158983 40478983 NNNN