Just a few strides away from the snowmobile, Doug Chabot knew that something was off. His uphill-equipped skis sunk deep into the snow, deeper than they should have. Weak snow, he noted, as he followed the track left by his partner’s skis. The two figures ascended the slope of Lionhead Ridge, a popular backcountry skiing area in southwest Montana, just north of Yellowstone National Park. It was November 24, and snow was falling. Little had come down over the past month; some patches were so thin that Chabot, an avalanche…
