May 9, 2023
A prolonged period of well-below-average spring temperatures combined with an above-average winter snowpack created a dynamic breakup of the Mosquito Fork of the Fortymile River. This resulted in ice jams and flooding. April temperatures were well below normal, and when temperatures began to warm in early May, it melted the low-elevation snowpack quickly. Because of the relatively quick addition of snowmelt onto strong ice, the ice was more susceptible to jamming and floods.
Source: NOAA National Weather Service Storm Events Database (event 1086934). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Upr Tanana Vly Fortymile County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.