Mesoscale Discussion 2347
Issued as Mesoscale Discussion 2347 at · Valid:
Summary
Isolated large hail may occur through the next few hours across southeast South Dakota into Iowa.
Product Text
000 ACUS11 KWNS 090136 SWOMCD SPC MCD 090135 IAZ000-SDZ000-090300- Mesoscale Discussion 2347 NWS Storm Prediction Center Norman OK 0835 PM CDT Thu Oct 08 2026 Areas affected...Southeast South Dakota into Iowa Concerning...Severe potential...Watch unlikely Valid 090135Z - 090300Z Probability of Watch Issuance...20 percent SUMMARY...An elevated supercell or two may produce isolated large hail in the next few hours. The marginal magnitude of the hail threat will likely preclude a watch. DISCUSSION...Elevated convection has been expanding in a northwest-southeast band from southeast SD into IA. The convection appears to be rooted into the 850-700 mb layer in a zone of low-level warm advection on the northeast edge of an elevated mixed layer. Isentropic upglide will increase through early tonight on the nose of a modestly strengthening low-level jet, which will support a continued increase in storm coverage through at least 04z. Upstream low-level moisture is sufficient for MUCAPE in excess of 1000 J/kg and cloud-layer vertical shear is strong enough to support an elevated supercell or two the next few hours from southeast SD into IA. Relatively steep midlevel lapse rates and the possibility of some supercell structures suggest that the strongest storms could produce isolated large hail near 1 inch diameter. Current expectations are that the hail threat will remain too isolated/marginal to warrant a watch. ..Thompson/Gleason.. 10/09/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...FSD... LAT...LON 41739455 42209562 42919727 43279783 43559770 43399662 42929532 42309382 41849302 41609297 41509353 41739455 MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN