Montezuma – Like Wile E. Coyote inadvertently sawing off his own pedestal, Leif Borgeson punches holes with a long pole into a precarious snow cornice, checking the thickness beneath his feet.
“We’re looking for a place where we can drive a 10,000-pound Sno-Cat,” beamed his companion, avalanche consultant Hal Hartman, standing on the same 4-foot-thick ledge of wind-drifted snow that hangs over a dizzying slope.
A full year before most skiers will experience the extreme terrain of Montezuma Bowl, Arapahoe Basin’s anticipated 400-acre expansion, Borgeson and Hartman are on a exposed ridge at nearly 13,000 feet, measuring the dangers and calculating the odds in avalanche country.
With every snowfall and windstorm, every solar-soaked spring day and hard overnight frost, the snowpack changes in ways both subtle and overt, with each element providing a critical clue about the potential for catastrophe.
So now, even before the U.S. Forest Service has granted final approval for the expansion, the duo are digging pits in the snow and observing weather patterns, stomping on cornices and setting off explosives to trigger avalanches.
“Last winter, we made 32 field trips into the bowl just looking at snow,” said Borgeson, the ski area’s snow-safety supervisor. “Over the summer, we spent a fair bit of time looking for clues on the ground. And this winter, we’re just doing a lot more on-ground work.”
This kind of deliberate study comes when the stakes are high: Skiers and snowboarders increasingly are demanding extreme skiing – the steep and the deep – but they also assume it will be safe.
In recent years, an increasing number of resorts have added lift service and boot trails into notorious avalanche terrain such as Highland Bowl at Aspen Highlands and Breckenridge’s Imperial Bowl.
There also have been two fatal avalanches inside resort boundaries in the past three seasons, including one in May 2005 at Arapahoe Basin, which already has its share of avalanche terrain, notably its famed East Wall.
“We take avalanche work extremely seriously here,” said Alan Henceroth, A-Basin’s general manager. “Being where we are, this is absolutely the heart of avalanche country, and we’ve spent a lot of time the last few years … developing our plans in how we’re going to mitigate that.”
Hartman has spent more than a year developing an “avalanche atlas” of Montezuma Bowl, taking innumerable measurements of snow depths and slope angles, wind speeds and temperature gradients – the differences in temperature within the snowpack itself – to develop a sophisticated computer model that will help guide Borgeson in determining when the area is safe for skiing and when control work is needed.
“Montezuma Bowl will create some challenges for the ski area,” Borgeson told a group of avalanche experts at a conference last fall.
Among other concerns, the ski patrol must decide where to stow rescue equipment and how to determine safe routes for snow-grooming equipment.
But chiefly, he pointed to an aerial photo of the bowl, noting the steep, corniced west side – with slope angles that reach the avalanche prime of 30 to 45 degrees – as being the biggest concern.
“There’s definitely evidence that avalanches have impacted this area,” Borgeson said.
“We found quite a large number of large trees, 20-inch diameter trees, that had been broken off 30 to 40 feet in the air,” he said.
“That was pretty telling.”
