Return of snow brings reminders of avalanche dangers in Tahoe region

Christian Michael Mares posted a warning on his Facebook page last month about avalanche risks in the Tahoe region, telling his friends to “be safe out there and have a blast.” The following day, he allegedly triggered an avalanche by snowboarding in a restricted section of Sugar Bowl Ski Resort.

Mares was snowboarding near the highest points of the Sierra Nevada, site of the most dangerous avalanche activity in California. As Sierra ski resorts experience an abundance of snow after several years of drought, experts remind visitors that the area has the elements needed to cause avalanches: steep slopes, heavy snow and a lot of recreational users.

Of the 63 avalanche fatalities in the state since 1950, 32 occurred in the Tahoe region, compared to 20 in eastern Sierra locations and nine in Southern California, according to a Sacramento Bee analysis of Colorado Avalanche Information Center data. Most recently, an avalanche is suspected in the presumed January death of Carson May, a 23-year-old ski instructor at Sugar Bowl who disappeared while skiing in a massive winter storm a day before Mares’ snowboarding incident.

The most avalanche-prone section of the Sierra crest runs from Carson Pass south of Lake Tahoe, continues west of the lake through Desolation Wilderness and ends northwest of the lake at Donner Pass. All but one of the Tahoe-area fatalities occurred on or near the Sierra crest, and 90 percent of the 43 reported backcountry avalanches in the last seven years happened in that area.

At roughly this season’s midpoint, the Sierra Avalanche Center has received six reports of backcountry avalanches in which a person was caught, buried or injured. That’s on pace with the 12 recorded backcountry avalanches in the 2010-11 season, the last time the region received above-average snowfall.

A big increase in snow this season is bringing more skiers, snowboarders and other outdoor enthusiasts to the mountains, exposing more people to avalanches, said Don Triplat, executive director of the Sierra Avalanche Center. More than 90 percent of fatal avalanches are triggered by people rather than natural conditions, he said.

“We’re having the conditions that create avalanches,” he said.

Avalanches often form when existing snow packed on the ground cannot handle the additional load from new snow and a skier or some other mountaineer. The surface breaks, and snow layers below it come apart, quickly producing a violent flow of tons of snow that sends a person tumbling down the mountain and easily burying him or her.

Grooming on ski runs mitigates the risks by flattening and breaking up the snow. Resorts also make the trails safer by sending out ski patrols every morning to look for avalanche risks such as heavy snow formations on ridges and other weather patterns that can make snow unstable, including high wind and rising temperatures.

The Sierra crest receives the most snowfall in the Tahoe area, said Zach Tolby, a meteorologist specializing in snow forecasting at the National Weather Service office in Reno. More snow falls along the crest because of its higher elevation and proximity to the Pacific Ocean, the source of most of its storms, he said. The crest also casts a “rain shadow” that keeps moisture away from areas to the east.

An average of 410 inches of snow falls each winter at Donner Summit, according to the Central Sierra Snow Laboratory.

Steep slopes are signature features of Alpine Meadows and other popular ski resorts on the Sierra crest, including Squaw Valley and Sugar Bowl. Avalanches most often occur on slopes of 30 to 45 degrees, Triplat said.

In records dating back to 1950, 12 people have been killed in avalanches at Alpine Meadows, more than any other California location, while six have died at Squaw Valley and four at Sugar Bowl, according to Colorado Avalanche Information Center data. Four of the fatalities took place in backcountry locations accessed through the resorts.

Seven of the deaths were the result of a single avalanche, the most deadly in U.S. ski history, at Alpine Meadows in 1982, when the resort closed because of a punishing storm but some employees still died.

Liesl Kenney, spokeswoman for the company that owns Squaw and Alpine, said backcountry fatalities listed by the Colorado Avalanche Information Center at the resorts should not be attributed to the resorts. She added that “our top priority is the safety of our guests, and incidents involving guests inbounds at the resort are very, very rare.” A Sugar Bowl spokesman did not respond to inquiries about the fatalities.

Triplat said Sugar Bowl, Squaw and Alpine have had more deaths simply because they have far more avalanche-prone conditions than other resorts in the area – more snow and steeper slopes with a lot of skiers.

Avalanches have caused 44 deaths at California ski areas or backcountry locations accessed through the resorts. A fourth of those deaths happened when people were skiing inbounds, another fourth occurred when they were skiing just outside resort boundaries, while the rest happened to resort employees or visitors involved in other activities such as snowshoeing or otherwise playing in the snow.

Ski patrols survey the resorts regularly to ensure they’re free of avalanche risks and use explosives and other means to break up dangerous snow formations before the lifts open, said Michael Reitzell, president of the California Ski Industry Association.

“The resorts have done a tremendous job with mitigation,” he said.

Relatively few people have been killed by avalanches while skiing resort trails, he said. Resorts typically have little control over skiing in adjacent backcountry areas because they’re often located on Forest Service land open to the public, he said.

At Squaw Valley and Alpine Meadows, ski patrols analyze snow and other weather data before performing control efforts, including the use of artillery to break up potential avalanche formations, said Kenney. She said ski patrols are highly trained and participate in industry committees to develop best practices.

As of Feb. 1, Squaw Valley had conducted avalanche control efforts 22 days this season, said Will Paden, the resort’s avalanche control director. Ten of those days required intensive efforts, with the ski patrol detonating more than 500 hand charges in the snow before opening the resort to customers, he said. The patrollers light a fuse on the charge, then toss them into the snow. The explosions send a relatively small amount of snow down the hill, but the patrollers launch them from a location where they think they’re safe from a resulting avalanche.

“It sounds like a battle,” Paden said. “You can probably hear it miles away.”

Both Squaw Valley and Alpine Meadows have had casualties in recent years in the “battle” against avalanches. Andrew Entin, 41, died at Squaw Valley in 2009 when he and a fellow ski patrol member skied across avalanche-prone terrain to break it up because an explosive had failed to detonate, the Placer County Sheriff’s Office said at the time.

Three years later, Bill Foster, 53, was one of three ski patrollers setting off charges at Alpine Meadows “in new locations higher up the mountain than normal due to a heavier snow accumulation,” according to an investigative summary by Cal/OSHA. Foster was dug out of the snow only minutes after the avalanche but had suffered numerous injuries and died at a hospital hours later. Cal/OSHA fined Alpine Meadows about $20,000 for violations related to his death.

Paden said he could not comment on the deaths but noted the company has taken a number of steps to improve safety. Most significantly, Squaw Valley became the first resort in the Tahoe area to install a Gazex Inertia Exploder to help clear the mountain before the ski patrol works on the slopes. The resort started using the exploder this season, remotely controlling blasts of oxygen and propane gas and helping to dislodge snow on one of the resort’s steepest slopes.

As resorts turn to technology and other means to improve avalanche control, skiers and snowboarders are increasingly visiting backcountry areas where such controls are nonexistent, said Triplat of the Sierra Avalanche Center. The center, a joint effort of the Tahoe National Forest and a nonprofit, instead relies on providing information to backcountry visitors to protect them, he said.

The center’s forecasters ski the backcountry daily and consult weather conditions to produce daily advisories about avalanche risks on its website. However, backcountry skiers need much more information to safely venture onto ungroomed slopes, Triplat said.

At minimum they need to take a 24-hour course on avalanches and use safety equipment that costs about $500, Triplat said. The equipment includes a transceiver, probe and shovel to help fellow skiers find and remove buried skiers. People interested in backcountry skiing can also turn to guides who specialize in such trips.

Backcountry skiers should focus on staying out of avalanches.

“Once you’re in an avalanche, you pretty much have no say in the matter,” said Triplat, adding that a quarter of the people who die in avalanches are killed by trauma, with the rest struck down by asphyxiation.