NWS forecasts earlier breakup dates, elevated ice jam flood risks across Alaska

NWS Spring Flood Potential April 14, 2020

ANCHORAGE, Alaska (KTUU) - The National Weather Service's Alaska-Pacific River Forecast Center released its site-specific spring breakup outlook Tuesday, forecasting not only a statewide breakup several days earlier than normal, but also a higher risk of ice-jam flooding across much of the state.

"The ice jam flood potential across Interior Alaska is greater than normal this year compared to past years," River Forecast Center hydrologist Dave Streubel said. "This is a result of primarily the really heavy snowfall they received over interior Alaska throughout the winter.

"The concern is with the really heavy snowfall at the valley floor," he said, "that will get a rapid warm up here later in April. And all that runoff will enter into the river system and with ice cover that we do have, the likelihood of getting an ice jam that cases flooding is increased."

Alaska has not seen a major ice jam flood since 2013, when an ice jam formed at Bishop Rock on the Yukon River on May 26 and backed up more than 40 miles of ice before it broke six days later. In that time, the village of Galena was flooded, homes were forced off their foundations and most of the residents were evacuated.

"The potential is there for something like that to occur, more so than at least the last four or five years," Streubel said. "We haven’t had a real big ice jam flood since then, but the conditions this year, with the increased snow pack, the relatively normal ice thickness and the potential for a rapid warm up here as we get closer to May, do indicate that something like Galena of 2013 or Eagle of 2009 or some of the ice jam flooding that we’ve had on the Kuskokwim river could occur this year."

Streubel said NWS has been in communication with villages that are at higher flood risk than usual, and says that the there is still uncertainty in the forecast but that it will be updated throughout April as more data is collected.

You can learn more about the forecast here.

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