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Thick ice doesn’t necessarily mean a late breakup

Published: Apr. 2, 2021 at 6:42 PM AKDT
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ANCHORAGE, Alaska (KTUU) - It’s that time. Alaskans are starting to look toward the breakup on the Tanana River. The tripod for the Nenana Ice Classic is set and guesses must be postmarked by Monday, April 5.

The Nenana Ice Classic has been going on for 105 years with breakup days ranging from April 14 to May 20. Based on those dates, river breakups are variable.

“It’s really the balance between the force of all the melt water entering into the river system flowing downstream and running into that solid river ice,” said Kyle Van Peursem, hydrometeorologist with the Alaska-Pacific River Forecast Center. He says there are three factors that go into breakup — ice thickness, snowpack and temperatures.

“But really we’re finding, it’s what your temperatures are like leading up to breakup,” said Van Peursem. “So April temperatures are really important.”

As of April 1, 2021, there were 45.3 inches of ice on the Tanana River, according to the Nenana Ice Classic webpage. That’s almost four feet of ice, but it’s nowhere near the highest amount since 1989. Thick ice doesn’t necessarily correlate to a late break up.

The earliest breakup on record for the Tanana was in 2019. Early April ice thickness was about 25 inches that year. The latest breakup was May 20. That occurred in 1964 and 2013. In early April 2013, the ice was 49.3 inches. The thickest ice since 1989 was 58 inches in 1994. That year the ice went out on April 29.

April 2013 — the year with the latest break up — is the third coldest April on record for Fairbanks.

According to Van Peursem, 2021 snowpack and ice are above normal for the Yukon River but about normal for the Interior.

“For the Tanana, everything is right around normal,” he said. “We have a little bit above normal snowpack, our ice thickness is normal, our temperatures are normal. But, we’re heading into April and the temperatures are still expected to be well, well below average, through at least mid April.”

The Climate Prediction Center puts all of Alaska at a strong or moderate tilt toward colder than normal temperatures for the six-to-10-day outlook.

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