Tonight’s upcoming winter snow storm for the Interior may slow down some river break-ups this month. But the Kuskokwim and Tanana Rivers have seen record early breakups this year, and it’s likely the Yukon will follow suit.
A few factors are contributing to this spring’s early river breakups, but primarily its warmer than normal temperatures.
“Throughout the state, the general trend has been a below average number of accumulated freezing degree days.” said National Weather Service Alaska Pacific River Forecast Center hydrologist Crane Johnson in a recently posted statewide breakup forecast video.
Johnson says the warmth has had an obvious effect on river ice.
“It’s not competent ice. It has no strength left to it,” National Weather Service hydrologist Karen Endres said.
Endres says river ice thicknesses averaged about 75 percent of normal coming out of the winter. Combined with above normal spring temperatures, and generally below normal snow melt run off, early and uneventful mush outs are more the trend.
”Not a lot of ice jams this year,” Endres said. “Much more of a thermal breakup.”
Endres points to the Kuskokwim and Tanana Rivers, which both went out record early and largely uneventfully, but she’s cautious about predicting similar for the Yukon.
”We are not, at this point, expecting records like we have had for the Nenana Ice Classic and a few other rivers that have gone out exceptionally early,” Endres said. “But we are expecting a fairly early breakup”
“There’s no evidence of anything going on currently.” said longtime Eagle resident and National Weather Service observer John Borg.
Borg reported Friday that the ice had yet to take on the darkened look it does before breaking up, but suspected it to transition fairly soon.
“I’m rather certain that it’s gonna break up before the first of May, but it all depends on how warm it starts getting during the day,” Borg said.
The earliest the Yukon River has gone out at Eagle is April 25th, and the median breakup date over the last 40 years is May 4th.
Dan Bross is a reporter at KUAC in Fairbanks.
