Winter Weather and Spring Avalanches

By Lucas Stewart, Staff Writer

It is formally spring – at least on the calendar – and a good time to look back at winter and breathe a sigh of relief. 

UAS campus was closed for the first two days of spring semester, due to heavy snowfall followed by freezing rain, a hassle for students and faculty, but UAS Facilities was ready, said Emergency Management Planner Ryan Sand.

Keeping campus safe is a collaborative effort, Sand said. The facilities crew begins removing snow and ice in the early hours of the morning, long before classes start.

“There’s a planning and organizational structure, with a heavy equipment certified facilities crew and school staff at the frontlines of that structure that ensure the roads and walkways are clear,” Sand said. 

National Weather Service data indicates that 2022 has not had record-breaking snow, but rainfall is a different story. Normal rainfall accumulation for this time of year averages around 12 inches. By the end of February, Juneau had 22.82 inches, according to the NWS website. Total rain accumulation between Jan. 1 and March 20 was 25.95 inches, nearly double the rain received last year at this time. 

Before the new year, snowfall was higher and temperatures were colder than normal.  Then Juneau rang in the new year with more than a foot of snow on New Year’s Eve. 

How does all of this weather affect the various outdoors activities that Alaska offers its residents? 

“There’s an inherent risk involved in any outdoor endeavor,” said UAS Assistant Professor of Outdoor Studies Forest Wagner.

“Anytime there’s snow on the ground there’s potential for it to slide, and if you have a slope and snow there’s a hazard of an avalanche,” Wagner said. 

Assessing the risk of an avalanche requires awareness of the accumulation of snow and the solidity of the snowpack.

“Snowpack and the snowpack history as it relates to weather is really important when managing the risk of avalanche,” Wagner said. “So you can have a really nice day and be outside and have a weak layer in the snowpack that’s triggered, either by human or by thaw, and hazard in those instances really goes up.” 

This year in particular hasn’t been more or less risky than any year prior in terms of avalanche and outdoor safety. However, one unique aspect Wagner noted was the amount of dry snow that fell a couple months ago when Juneau was  having winter storms and jumps in temperature.

“One of the things about this year or that’s been unique is that we had almost two months of clear cold weather when we did have storms, the snow fell, and it was very dry,” Wagner said. “So, one of the big avalanche cycle concerns was the thaw in late January when it went from 0 degrees Fahrenheit to 32 degrees Fahrenheit in one day.” 

Wagner compared this snow to the heavier, more wet snow that fell in March as the weather got slightly warmer. The wet snow sticks on top of the drier snow from previous months. Wagner uses an analogy of an “upside down cake,” where the lighter dry snow on the bottom is unable to support the heavy snow on top, and creates a greater risk for slides. 

“In physics, or in structures, we want a really strong foundation and then lighter stuff on top, and so, when the snowpack is upside down, it sets itself up for avalanche cycles or for instability,” Wagner said. 

Avalanche danger changes by the day and some days will be worse than others depending on a variety of factors, according to Wagner. Rain, snow, air pressure, snowpack, and the like can determine safety in the backcountry. While there is really no way to prevent avalanches, you can have the knowledge and resources to prepare for them.

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