Avalanche center hopes Colorado can avoid repeat of deadly 2020-21 winter
12 fatalities statewide were the most since 1992-93
The Colorado mountains are notorious for receiving substantial snowfall in October and November, then getting a dry spell that results in a rotten base layer.
Last winter was the poster child for those conditions, and it resulted in a deadly winter for avalanches. The 12 fatalities were the most recreational avalanche deaths since 1992-93 and double the state’s 10-year average, according to a recent summary by the Colorado Avalanche Information Center in The Avalanche Review, a publication by the American Avalanche Association.
“Only pre-WWII mining days saw seasons with more avalanche fatalities,” wrote Brian Lazar, deputy director of CAIC.
In the Aspen zone, there were 589 avalanches observed and reported to CAIC in 2020-21 season, considerably more than the 351 slides recorded in the Aspen area the winter before.
In an interview with The Aspen Times on Monday, Lazar said this winter is starting off with generally safe conditions that could change by the end of this week.
“It’s not the same as last year,” Lazar said. “The difference is this year the early-season snow cover is much less contiguous compared to last year. It really is confined to the northerly, maybe east-facing slopes at really high elevations, so the upper stretches near treeline and then alpine.
“At this point last year we had snow cover much more contiguous across the landscape, which then made the weak layers much more contiguous across the landscape, so when we finally got snow, it built slabs and we saw bigger avalanches.”
Lazar will be the featured speaker at Mountain Rescue Aspen’s avalanche awareness workshop Dec. 17 (see related story).
After a dry stretch to start December 2020, it started snowing Dec. 10. Across the state, there were 93 human-triggered slides the following week as powder-starved backcountry travelers were eager to finally get outdoors. It was the most human-triggered avalanches triggered in a week in Colorado, according to CAIC. As snowfall kept piling up, the slides got bigger. The first avalanche fatality occurred on Dec. 18 when a skier got caught, buried and killed west of Crested Butte.
Another dry period in January 2021 created another weak layer and established conditions that resulted in more deadly slides once snowfall returned.
The weather at the start of winter has been unusual. Although there were a couple of storms in the Aspen-area high country in October and November, there were also pronounced dry periods with cold nights.
“We have generally safe avalanche conditions (as of Monday) because we just don’t have any snow,” Lazar said. “The good news (of) these warm, really dry conditions is that many slopes melted back to bare ground. We kind of get to start over in all those places, so that is good news for us.
“But it’s not going to be case everywhere,” he continued. “The places that held onto the snow — they’re going to be the first to produce the big avalanches — are those high north, northeast maybe east-facing slopes in the alpine.”
The recent dry stretch, he said, has been a good time for backcountry travelers to take note of the slopes that held snow because they will likely develop into problem areas in the future.
“It’s just weak, sugary snow from top to bottom in places that it survived,” Lazar said.
As of Monday, the dry spell reached 11 days, according to aspenweather.net.
With multiple days of snow in the forecast, backcountry travelers must realize “we’re in store for a fairly dramatic change in avalanche conditions,” Lazar said. “We have our first storm on the horizon this week, which is very much welcome news but it’s going to be a substantial amount of snow.”
The first pulse was forecast for Monday night into Tuesday. That probably won’t change the hazard level, according to Lazar. But if the Aspen-area mountains get snowfall in the upper end of the forecast, between one and two feet could fall by the end of the week.
“We want people to realize winter is here, it’s coming,” Lazar said. “This is going to be a very dynamic week, so don’t get complacent. Check the forecast because things are going to change very quickly.”
A daily forecast is available at the CAIC website at http://www.avalanche.state.co.us.
In the 2020-21-winter assessment for The Avalanche Review, Lazar noted that the Colorado Avalanche Information Center tried several ways to get the word out last year about the hazardous conditions, but still saw the high number of fatalities.
“We hope the historic numbers of avalanche fatalities, multiple-involvement accidents and multiple-fatality accidents are just anomalies and not the sign of a worrisome trend,” he wrote.
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