Thunderstorm Wind in Charles Mix County, South Dakota

Thunderstorm wind gusts caused a driver in the westbound lane of South Dakota Highway 46 between Pickstown and Wagner to lose control, cross over into the eastbound lane, and collide head-on with an oncoming car, which resulted in the indirect fatality to both drivers.

A cluster of thunderstorms developed across eastern Montana and the western Dakotas during the morning hours. These storms organized and turned southeastward, feeding on rich inflow of post-frontal air with up to 3000 J/kg of MLCAPE and over 1000 J/kg of DCAPE. Along with strong storm-relative shear, parameters favored development of a strong cold pool and balanced mesocyclone, which spread southeast with the cluster and developed a strong and long-duration severe wind event which traversed South Dakota, southwest Minnesota, extreme northeast Nebraska, and northwest Iowa during the afternoon and early evening. The storm was classified as a derecho, and featured numerous wind gusts from 70 to 100 mph and considerable damage to trees, crops, powerlines, and structures along its path. In some cases, severe wind gusts persisted for more than 30 minutes.