Aug 5, 2023
An outflow boundary from earlier day convection focused a gradient of instability and storm development with additional destabilization from heating by early afternoon. Boundary interactions from sluggish storms led to training of heavy rainfall cores, as well as a couple brief tornadoes. Extensive flooding resulted in a state disaster declaration for Sioux County.
Source: NOAA National Weather Service Storm Events Database (event 1129823). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Sioux County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.