Mesoscale Discussion 2318
Issued: · Valid: –
Summary
Isolated instances of marginally severe hail and wind are possible this evening across portions of southern Missouri, southern Illinois, southern Indiana, and far western Ohio.
Product Text
000 ACUS11 KWNS 202338 SWOMCD SPC MCD 202338 OHZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-210145- Mesoscale Discussion 2318 NWS Storm Prediction Center Norman OK 0638 PM CDT Sun Sep 20 2026 Areas affected...portions of southern Missouri...southern Illinois...southern Indiana...and far western Ohio Concerning...Severe potential...Watch unlikely Valid 202338Z - 210145Z Probability of Watch Issuance...20 percent SUMMARY...Isolated instances of marginally severe hail and wind possible this evening. DISCUSSION...A stationary front extends southwest to northeast across portions of southern MO, southern IL, southern IN, and into western/central OH. Daytime heating has yielded a moderately unstable air mass along and south of this feature. Thunderstorm activity has developed across several regions along and south of front. A more focused region of forcing for ascent is moving out of eastern OK into southern MO, which will likely lead to an uptick in thunderstorm activity through the evening. Multi-cell clusters will be favored given the more parallel component of deep layer shear to the front in this region. Given that deep layer shear is mostly confined along and north of the front, mode will be fairly unorganized. However, a few stronger clusters may produce strong to severe wind through the evening. Further east across portions of southern IL, IN, and western OH, transient supercells have developed near and south of the front. Within this region, deep layer ascent is more negligible aside from weak frontal convergence. Additionally, though the air mass remains moderately unstable, warm mid-level temperatures will likely work against sustained severe convection. An isolated marginally severe wind and hail risk may continue for another hour or so past sunset. ..Thornton/Guyer.. 09/20/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ILN...LMK...IWX...IND...PAH...ILX...LSX...LZK... SGF... LAT...LON 38009294 37649359 37129342 36549284 36489205 38818489 39298355 39908329 40208361 40338416 40418617 39279035 38009294 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN