Flood — Wrn Tanana Vly Wrn Yukon Vly, Alaska

2023-05-17 to 2023-05-21 · near Tanana, Wrn Tanana Vly Wrn Yukon Vly, Alaska

Event narrative

An ice jam on the Yukon River approx 100 miles downriver from Tanana caused minor flooding in the community.

Wider weather episode

A prolonged period of well-below-average spring temperatures combined with an above-average winter snowpack created a dynamic breakup of the Yukon River. This resulted in numerous ice jams and snowmelt flooding on the Yukon River. Breakup flooding began on May 12th in eastern Alaska in Eagle and ended on June 3rd in the Yukon River delta at the Bering Sea coast. The primary cause of this active flood year was a 1-2 week delay in breakup when compared to typical timing. 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. In addition to the late breakup, the snowpack this winter was 1 to 1.5 times greater than the climatological normal for interior and western Alaska. Significant ice jams and associated flooding on the Upper Yukon River resulted in large volumes of ice and water to move down into the Middle Yukon River.

View location on OpenStreetMap → (65.1702, -152.0773)

Source: NOAA Storm Events Database, event_id 1104127. Narrative written by the NWS forecast office that issued the report.