New snow atop faceted base equals unstable snowpack
By Summit Voice
SUMMIT COUNTY — Winter recreation turned deadly in the Rocky Mountains of Montana during the New Years weekend, as two snowmobilers and a backcountry skier died in separate avalanches, according to the Gallatin National Forest Avalanche Center.
With a thick layer of faceted crystals near the ground, the avalanche hazard spiked Saturday after a snowstorm hit the northern Rockies, and powderhounds ventured out into the backcountry in search of fresh snow.
Similar conditions are likely to prevail in Colorado when the snow comes. Visit the Colorado Avalanche Information Center online for more info.
One of the victims was 44-year-old David Gaillard, a longtime conservation advocate with Defenders of Wildlife. Gaillard was backcountry skiing with his wife in the Hayden Creek drainage, near Cooke City.
The slide fractured about 800-feet-wide and 1- to 3-feet deep then funneled down into a narrow drainage where the snow piled up more deeply.
In a separate accident, a snowmobiler also died in the mountains near Cooke City, while yet another snowmobiler triggered a slide and died east of Red Lion.
The Gallatin National Forest Avalanche reported on the incidents:
“The avalanche danger spiked on Saturday immediately after the storm. In two separate incidents a skier and snowmobiler were killed in avalanches near Cooke City. Further to the west, far outside our forecast area, a snowmobiler on Sunday was also killed in an avalanche east of Phillipsburg. With no new snow and minimal wind-loading, the snowpack is starting to stabilize as it adjusts to the new load. However, this is when stability assessment starts to get tricky. Avalanche activity and other obvious signs of instability are decreasing. Not all slopes are unstable, but a lot are. I’m more worried about human triggered slides this week than I was over the weekend. My advice is simple: Be conservative …
This what the forecasters had to say about the conditions:
“Yesterday Karl and I, plus two locals, investigated the avalanche that killed a backcountry skier on Saturday. The avalanche was triggered south of Cooke City up Hayden Creek. The slide was approx 800 feet wide, 250 feet vertical with a crown depth averaging 1-3 feet deep and 35 degrees steepness. Although the crown was wide, the gulley that the skier was buried in was only 50 feet across. The avalanche broke on facets, some at the ground, others higher in the snowpack. I will have a detailed report later in the week, as will Eric on the fatality on Henderson Mountain. I posted a few photos on the web with more to come.”
The Gallatin National Forest Avalanche Center has posted detailed info and photos online at this web page.