EF0 tornado in Gregory County, South Dakota

A storm chaser documented the initial touchdown of a tornado less than one mile northwest of Lucas, SD a bit southeast of the intersection of 283rd Street and 347th Avenue. The tornado then tracked southeast for around one mile, narrowly missing the town of Lucas but uprooting three large pine trees at 284th Street and 348th Avenue. After crossing the intersection, the tornado shredded the tree line just to the east of a hunting lodge. The tornado traveled across an open section before turning more southerly and again impacting a tree line at the mid-section line. The tornado crossed 349th Avenue and left a track in some mature corn before lifting just east of 349th Avenue. The tornado was rated EF0 with an estimated maximum wind gust of 85 mph. The average path width was 25 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.