City maps for future avalanche seasons

When spring finally approaches, the avalanche risk will decrease this season as the snow melts.

But snow returns every winter. And more variable winters don’t make the forecast easier, said Juneau’s avalanche expert.

“It’s getting more dynamic. Some years could be better, some years could be worse, “City and Borough of Juneau emergency program manager Tom Mattice said in a telephone interview. “It’s getting harder and harder to predict.”

Juneau had a brisk avalanche season between 2020 and 2021, including the city-recommended evacuations conducted from high-risk areas on Behrends Avenue in February.

Mattice recently made a series of recommendations to the Juneau Lands, Housing and Economic Development Committee, which he called the State of the Union. The recommendations were derived from a study by the Swiss Institute for Snow and Avalanche Research on Juneau’s avalanche risk, Mattice said.

“The bottom line is we’re doing our best with our limited budget,” said Mattice. “We try to provide as much information as possible with the available staff and resources.”

Suggestions in Mattice’s report include examining the city’s ability to obtain grants to aid buybacks of the riskiest homes on the Behrends Avenue avalanche slide. The city is currently exploring this option for the highest risk home and is considering it a pilot project, according to Mattice’s report.

“You have bought empty land in danger zones before. You’ve never bought houses in danger zones, ”Mattice said. “We have a chance with our most damaged home.”

According to the report, further recommendations are improved avalanche formation, improvement of the monitoring stations and the re-evaluation of the predicted avalanche paths. The report also noted that a major avalanche would affect access to or via downtown via Glacier Highway or Egan Drive, and that a second crossing would reduce the risk of being obstructed in such an event.

“That’s why we have an excellent study in draft form,” said Mattice. “The avalanche maps of the 1970s were created using hand-made equations.”

Improved data collection by relevant organizations also improves models and forecasting, Mattice said.

Avalanches, like the aftermath of an intentional avalanche on Thane Road, will continue to be part of Juneau’s winters. However, it is difficult to say what the future risk will be. (Peter Segall / Juneau Empire)

Rainier winters, warmer temperatures

Looking at climate trends in Southeast Alaska, Juneau can expect winters that will gradually become wetter and slightly warmer, said Rick Thoman, Alaska climate specialist at the Alaska Center for Climate Assessment and Policy, part of the University of Alaska Fairbanks.

“If summers stay where they are on average and rainfall increases, it means we get more rainfall in other parts of the year. For example right now, ”he said during a phone interview in March. “This could be a sign of the future, but we have to keep in mind that year-to-year variability will not go away.”

The year-to-year variability means there will continue to be good years and bad years, Thoman said.

“At the beginning of winter it was wet but warm, with comparatively little snow for Juneau,” said Thoman. “The second half was wet, but below normal temperature. This kind of variation between winters continues. ”

Higher rainfall rates at high altitudes may or may not affect risk, Mattice said.

“A lot of rain can mean a lot of rain. And a lot of rain could mean having a lot of snow, ”said Mattice. “More precipitation often means a more homogeneous snow cover. It’s such a wild card. ”

The February high risk period was caused by a hard, dry frost. More snow generally makes the snowpack safer, Mattice said, but not when a weak layer is buried in it.

“When you get cold, dry breaks, you get facets in the snowpack,” said Mattice. “Every season is different. This year that weak layer was buried super, super deep. We have a thick layer of snow with a weak layer. ”

The Alaska Department of Transportation and Public Services continues to fly avalanche defense missions on Thane Road. More are planned for the second half of April, said DOT spokesman Sam Dapcevich in a telephone interview. Avalanches were triggered there on April 15, which lost some snow in the slide.

• Contact reporter Michael S. Lockett at (757) 621-1197 or

Peter Segall / Juneau Empire Avalanches will continue to be part of Juneau's winters, like the aftermath of an intentional avalanche on Thane Road.  However, it is difficult to say how the risk will present itself in the future.

Peter Segall / Juneau Empire Avalanches will continue to be part of Juneau’s winters, like the aftermath of an intentional avalanche on Thane Road. However, it is difficult to say what the future risk will be.

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