Alaska hydrologists keep close eye on spring temps, flood risks

Concern is growing across interior parts of Alaska with the river ice breakup season just around the corner.
Published: Apr. 6, 2023 at 7:22 PM AKDT
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ANCHORAGE, Alaska (KTUU) - Concern is growing across interior parts of Alaska with the river ice breakup season just around the corner.

Hydrologists and forecasters with the National Weather Service are focusing on the upper Yukon area for the greatest risk of flooding this year.

“It is a fairly robust snowpack for like the Yukon drainages, for the upper Kuskokwim, for a lot of the sites draining the Alaska Range and into the Brooks,” said Celine Van Breukelen, a hydrologist with the National Weather Service Alaska Pacific River Forecast Center.

But it’s not just snowpack that’s a critical factor, but also temperatures.

“We’re going to be looking very carefully at the temperatures the end of April, into early May, because that’s going to be sort of that critical point where we’re going to be very concerned if we snap from a cold regime to a warm regime very quickly,” says Van Breukelen.

The sudden temperature changes would create rapid snowmelt and ice breaking up into large chunks, potentially causing big ice jams. Such was the case in 2009 when an ice jam 10 miles downstream of Eagle sent large ice chunks and flood waters surging through the small Eastern Alaskan village on the Yukon River. Much of Eagle suffered catastrophic flooding and structural damage.

Chief Karma Ulvi of Eagle is paying very close attention this year because of how the river froze.

“The river froze and then it raised quite a bit and it got pretty high and then it froze again,” Ulvi said. “So we’re not really sure if then it dropped after but the river froze again a lot higher than normal.”

Even though much of the town has since relocated to higher ground, Chief Ulvi still has concerns for the safety of the village residents and especially the elders.

“The city and the village will be cut off from each other if the road floods down on the low areas,” Ulvi said. “And so the airport is actually in town and the clinic is up here. So in case of an emergency or we need to medivac a patient that’s very difficult to cross that area. We have to use the back trails.”

For areas farther downstream in the lower Yukon and Kuskokwim deltas, where the snowpack is not as high, forecasters go back to the temperature wild card.

“What we’re looking at which is sort of concerning from a hydrology perspective is that things in the Interior are pretty cold for right now and the climate predictions have us being colder through the middle of the month. And that just makes us a little bit more concerned from a flood risk perspective, because we’re going to be holding on to that snowpack a lot longer,” Van Breukelen said.

So regardless of how fast or how slow the snow melts, the ice breaks and the rivers rise, now is the time to start preparing and looking at those emergency evacuation plans.