EF0 tornado in Bon Homme County, South Dakota

A trained spotter observed the rapid spin up of a tornado to the west of his location 5 miles south of Avon, just north of 307th Street and west of 405th Avenue. The tornado tracked northeast, and moved into a farmstead as it crossed 306th Street. Roof panels were blown off a farm outbuilding, with doors on the building bowed inward. Several trees on the farmstead suffered damage to large branches. The tornado continued to track northeast for around another half mile before lifting. Average path width was 20 yards.

A frontal boundary provided focus for convective development across south central South Dakota during the very late afternoon and early evening as a strong impulse moved in the southwest flow aloft. Initial discrete cells produced spotty hail and damaging wind, with MLCAPE values around 1500-2000 J/kg and 45-55 knots of deep-layer shear. As cells spread eastward and developed into a line, the increase in low-level jet during the evening quickly increased the 0-3 km shear to 35-40 knots. Three QLCS tornadoes occurred within the city limits of Sioux Falls. In addition to the tornadoes, widespread wind damage to trees and spottier damage to residences were reported across much of the city. A total of nine people were injured in the storms around Sioux Falls. Repeated cells resulted in flash flooding by later evening and into the overnight hours.