The Flathead Avalanche Center is warning backcountry users that dangers still exist in the mountain snowpack despite on onset of spring.
In its final advisory of the season April 15, the center said an above average snowpack and a wet outlook for the coming months mean that avalanche concerns “aren’t going away anytime soon.”
Snowpack in the Flathead Basin is at 152 percent of average, with much of the high terrain above 6,000 feet holding more than 12 feet of snow. And new snow is still coming down. Big Mountain in Whitefish received more than 15 inches of new snow April 13, and was expected to pick up an additional 2-4 inches on Tuesday.
Loose wet avalanches are the most frequent avalanche problem in the spring, as rising temperatures, sun and rain become factors, the center warned. “These slides release from a single point but produce a surprisingly powerful amount of debris,” said avalanche center director Zach Guy in the spring advisory.
Rollerballs, pinwheels, or natural sluffs all signal instability and are signs that backcountry users should move to different terrain with colder snow, Guy warned.
Another concern in spring is melt-water in the snowpack that can create “glide avalanches.”
“These conditions can result in very destructive debris that runs across all elevation bands onto bare ground,” Guy said.
Backcountry skiers and snowmobilers should avoid traveling below slopes with signs of glide cracks.
In general, backcountry users are advised to travel early while the snowpack is frozen. If the snowpack doesn’t refreeze overnight, avoid steep terrain. Post-holing, Guy warned, “is a sign you’re not welcome in avalanche terrain.”
“Continue to assess the weather, snowpack and terrain, and practice safe travel techniques until the snow melts,” he added.
There were three avalanche fatalities in Montana this season, including a 39-year-old Bozeman man who died Saturday in a slide while skiing in the backcountry on Saddle Peak near Bridger Bowl.
The center will continue to update its social media with critical observations. Visit www.flatheadavalanche.org for the complete spring advisory.