Flood in Yukon Delta, Alaska

An ice jam formed in the Yukon River Delta on May 27th on the South Mouth of Yukon River near Alakanuk. Extensive overland flooding occurred with minor flooding Emmonak. Low-lying roads were submerged, including access road to the airport. In addition, numerous homes which are elevated on pilings in Emmonak had water beneath them along with extensive property flooding. The ice jam released on May 28th and ice was reported to be moving out through rotten shore fast ice into the Bering Sea. A Flood Watch was issued on May 23rd and upgraded to a Flood Warning on May 27th. All flood products were canceled on June 3rd.

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 at the community of Emmonak. 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 and Middle Yukon River resulted in large volumes of ice and water to move down into the Yukon Delta.