Thunderstorms that started up in Montana during Independence Day moved into the northwest region of South Dakota during the first part of July 5th. These thunderstorms then moved into an area where the environment supported strong to severe thunderstorms.
These thunderstorms developed into a line of thunderstorms creating the derecho that spread across eastern, South Dakota and into parts of Iowa. The maximum wind gust reported during the event was one mile west of Howard with a 99mph gust. There were many reports of hurricane-force winds across central and eastern, South Dakota that caused numerous damage.
Photo Credit: Harrisburg Parks and Rec.
Thunderstorm Wind Gust Report:
Howard: 99mph Huron: 96mph Wall Lake: 85mph
Timber Lake: 84mph 7SW of Butte: 82mph
Forestburg: 81mph Sioux Falls: 80mph Spencer: 80mph Cavour: 80mph Woonsocket: 80mph Parker: 79mph Salem: 78mph Highmore: 78mph Springfield: 77mph 7NE of Onida: 77mph
Alexandria: 76mph Agar: 75mph Mitchell: 75mph Whitlocks Bay Rec: 71mph 8NW of Usta: 70mph Wolsey: 70mph Stephan: 70mph
Photo Credit: South Dakota Highway Patrol
There were only a few reports of large hail, but some of the reports were impressive. Hail to the size of softballs was reported in Promise and two miles north of Timber Lake in north-central, South Dakota. Other reports of tennis ball size hail near Firesteel and golf ball size hail near Glencross, Bison, and Highmore.
Down in southeast, South Dakota, four miles northeast of Tea and four miles southwest of Sioux Falls received quarter-size hail.
There were a couple of tornado warnings during the event but no confirmed reports of any tornado touchdown.
Photo Credit: South Dakota Highway Patrol