Break Up Begins In Middle Kuskokwim, Upper and Lower River Still Holding

Apr 19, 2016

Napaimute, looking downstream. April 18, 2016. Photo courtesy the National Weather Service, Alaska.

The earliest break up on record has begun in the middle Kuskokwim, but ice is still holding in the upper and lower sections of the river. That’s the results from an aerial survey by the National Oceanic and Atmospheric Administration, which photographed the Kuskokwim from the Holitna River tributary to Napakiak on Monday.

Crane Johnson, National Weather Service hydrologist, says the crew observed in place sheet ice upstream of the Holitna with some large, open areas.

He says the ice sheet at Sleetmute has shifted. The river from Red Devil to 15 miles upstream of Napaimute has in place sheet ice that’s starting to weaken.

Open water begins just upstream of Napaimute to just upstream of Aniak with ice clinging to the banks. Then Johnson says, around Aniak, chunk ice and small pans have formed an ice jam.

“Then it was sheet ice from Aniak all the way down to the Kuskoquak with some open areas and some shifting but mostly sheet ice that was beginning to weaken,” Johnson said. “And then downstream from the Kuskoquak it was in place ice with larger open areas, and the ice was darker and it weakened more.”

Johnson says it’s typical during a thermal break up, or mush out as it’s also called, for break up to occur at multiple points along the river. That’s different from typical break ups where a main ice front moves downstream.

“The important thing right now is those areas that have open water at Napaimute and Chuathbaluk, they’ll see heavy runs of ice as the upriver continues to break up,” he said.

Which means, boaters, watch out.

Johnson says Wednesday the National Weather Service will dispatch its annual River Watch team to Aniak. The crew will spend a few days flying the river, sending ice reports to communities and stopping in various villages to help residents prepare for potential flooding. A precaution, Johnson says, since a mush out reduces the likelihood of flooding occurring.

According to NWS archives, the earliest break up on record for Aniak since 1957 occurred April 24, 1998. The earliest break up on record for Kalskag since 1938 occurred April 22, 1940. And the earliest break up on record for Crooked Creek since 1938 occurred April 13, 1960.

Official break up dates for communities with open water along the middle Kuskokwim have not been designated. David Streubel, NWS hydrologist, says the river’s main ice front moving past communities usually classifies break up. With the mush out changing that definition, Streubel says the River Watch team will consult with these communities on their selected break up date.

You can view aerial pictures from the NOAA flight here.