May 22, 2018
A moderately unstable but very moist atmosphere was in place over southwest North Dakota when numerous thunderstorms developed in the late afternoon. Initially, large hail was the main threat, with the largest hail being half-dollar size falling in Grant County. The main threat then shifted towards heavy rainfall, with flash flooding occurring near the town of Haynes in Adams County, where US Highway 12 was closed for approximately two miles due to deep water over the road.
Source: NOAA National Weather Service Storm Events Database (event 751524). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Adams County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.