EF1 tornado in Gregory County, South Dakota

A storm chaser documented the initial touchdown of a tornado a little over a mile to the northwest of Dixon, SD just north of 276th Street in an open field. The tornado traveled to the east-southeast for around 2 miles before it impacted the north side of a farmstead where it damaged the shelter belt and destroyed an older outbuilding. As it continued along the path, it crossed near the intersection of SD 47 and SD 44 where it downed power poles and twisted a couple of SDDOT truck shelters. The tornado then traveled over mainly open fields for another 2 to 3 miles before taking a slight turn more to the southeast. After around 5 more miles on a southeastward path, the tornado lifted in an area of more uneven terrain. The tornado was rated EF1 with an estimated maximum wind gust of 110 mph. The average path width was around 100 yards.

Two distinct supercell clusters developed across central South Dakota during the late afternoon of July 28 within a highly unstable environment (MUCAPE up to 5000 J/kg) ahead of an eastward advancing surface front. The southern supercell cluster produced three tornadoes across Gregory County, the strongest of which was rated EF2.

Scattered severe wind gusts were reported across southeast South Dakota as the thunderstorms moved east before the two clusters merged near and south of Sioux Falls. Aided by increasing deep layer shear from the north, a linear structure rapidly developed with a derecho racing eastward into northwest Iowa. Winds gusted from 80 to 100 mph along the derecho's path with widespread tree and structural damage across the area. In addition, three embedded short-lived tornadoes were documented within the line of thunderstorms.