Deaths highlight avalanche risks in Sierra -- Surviving an avalanche

The recent spate of avalanches at Sierra ski resorts, some of them deadly, offers a reminder of potential peril when heavy snow layers the slopes under certain conditions, experts said Wednesday.

As always, the biggest danger of snowslides lies in the backcountry. But recent events show there’s risk even at places carefully monitored by trained personnel paid to ensure safety of skiers and snowboarders now massing at ski resorts for the holidays.

After two skiers escaped serious injury during a Sunday avalanche that a witness said was triggered by snowboarders at Squaw Valley, two more slides occurred at Sierra resorts on Monday. One buried and killed a snowboarder at Donner Ski Ranch, and the second claimed the life of a veteran ski patroller at Alpine Meadows.

The slides occurred after storms dropped up to 5 feet of snow over the weekend, with a Christmas storm adding more than a foot. In the backcountry, recent snows settled atop an older snowpack that is weak and prone to fracturing into slides, experts said.

“It’s a very real danger, and it will take some time to settle down,” said Denny Hogan, winter sports specialist with the U.S. Forest Service’s Truckee Ranger District, which monitors the backcountry for avalanche danger.

On Wednesday, the Sierra Avalanche Center rated the danger of backcountry slides as considerable both above and below the treeline on slopes facing north, northwest, northeast, east and southeast with a steepness of 32 degrees or more.

All other slopes had a moderate risk, with “large, destructive, human-triggered avalanches likely” and natural slides also possible, the center said.

“Dangerous avalanche conditions exist,” the center’s statement said.

With fresh, wet snow sitting atop the weak snowpack left from wet, warm storms earlier this month, the risk is considerable, Hogan said.

“That existing snowpack is failing, and you’re seeing more natural avalanches and people triggering avalanches,” Hogan said. “You can have large avalanches, and that’s what we’re seeing now.”