Thermal Break Up or Mush Out Likely Underway

by Daysha Eaton on April 30, 2014

Kuskokwim River near Aniak. - Courtesy of Bethel Search and Rescue

Kuskokwim River near Aniak. – Courtesy of Bethel Search and Rescue

A mild winter in Southwest Alaska combined with low snowfall is resulting in what hydrologists say will likely be a “thermal break up,” and what some call a “mush out.

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There’s open water below Aniak and ice is moving at Kalskag, according to Bethel Search and Rescue. All side sloughs, short cuts, and tributaries are wide open or at least broken up.

The Alaska River Watch Program launched its first flights late Tuesday. Eric Holloway with the National Weather Service River Forecast Center was on the flight. He says compared to last year, the river is way ahead of schedule.

“We’re almost a month early at this point from last year. Right now it’s looking like a mushout at this point because there’s just not enough water in the hills to push the ice that may be left rotting in place.”

Holloway says that conditions make flooding less likely, but people should still be prepared for anything.

“The likelihood of flooding this year is very low. But I still want people to realize that there’s still ice that can come down, especially if you get into your boats a little early with all these openings – still be aware that there’s still some runs of ice up the Oscawalik River. We had a report from Red Devil that ice had moved and shifted there. So there are still some runs of ice that will come down from upstream that people need to be aware of.”

Temperatures have been in the 50s and a predicted to reach nearly 60 degrees in Bethel on Friday. Alaska River Watch is a partnership between the state department of homeland security and emergency management and the National Weather Service. More flights are planned to assess breakup in the coming days.

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