A powerful winter storm triggered an avalanche near Frog Lake in the Castle Peak area north of Interstate 80 at Donner Summit on Tuesday, leaving eight people dead, one missing and six survivors, authorities said Wednesday.
The avalanche struck in backcountry terrain — not a groomed ski area — during the final day of a three-day tour organized by Blackbird Mountain Guides. According to The Associated Press, four guides and 11 clients had been returning to the trailhead after staying in remote Frog Lake huts. The group included nine women and six men, ranging in age from 30 to 55.
Nevada County Sheriff Shannan Moon said Wednesday that crews located six survivors, including one guide and five clients. Two of the survivors were injured; one was stabilized and released, and the other remains under treatment. Their injuries were reported as non-life-threatening, per AP.
“Our Regional Dispatch Center received a 911 call reporting the avalanche,” Moon said at a press conference Wednesday afternoon. “Extreme weather conditions is an understatement.” Gale-force winds made it nearly impossible to see, and helicopter rescues were not possible.
Rescue operations involved multiple agencies, including the Nevada County Sheriff’s Office, Truckee Fire, Placer County Sheriff’s Office, Washoe County Search and Rescue, and Tahoe Nordic Search and Rescue, all coordinated through California Office of Emergency Services.
According to wire reports, teams departed from both Boreal Mountain Ski Resort on the south side of the highway and the Tahoe Donner Alder Creek Adventure Center on the north side, with roughly 50 personnel in total.
Crews were able to reach survivors after skiing roughly two miles through treacherous terrain, using snowcats and other vehicles where safe. Moon said conversations with survivors were facilitated through iPhone SOS features.
Moon said in a live press conference that eight of the nine missing skiers have been located deceased. The ninth skier remains missing, and Moon cautioned that search efforts are ongoing but hampered by weather.
“It’s not a resource issue, it’s weather,” she said. The cause of death for the eight skiers has not been confirmed.
One of the nine skiers who had been missing — and among the eight located deceased — was the spouse of a Tahoe Nordic Search and Rescue team member.
The Castle Peak area has proven hazardous in recent weeks. Last month, a snowmobiler died in an avalanche in the region. Moon said that avalanche was roughly a mile away from Tuesday’s avalanche involving the skiers.
Families of the victims have been informed that the mission has shifted from rescue to recovery, the sheriff said.
How does an avalanche start?
Avalanches start when snow piles up and slowly changes over time due to temperature differences in the snowpack.
Experts explain that heat from the ground causes water vapor to rise, reshaping the snow crystals. In stable conditions, they round off and stick together, forming a strong, solid layer. In unstable conditions, crystals remain sharp and angular, creating weak layers filled with tiny air pockets — like a fragile Jenga tower, as The New York Times describes it.
When new snow falls or wind pushes snow into drifts, it can form a heavy slab atop these weak layers. If the weak layer can’t support the weight, it collapses, sending the slab sliding downhill.
This sudden movement is an avalanche, and even a small trigger, like a skier or snowboarder, can set it off.
Is Utah at risk?
The Utah Avalanche Center has issued a “high” avalanche danger warning from Wednesday through Thursday.
According to the center, areas at risk include Logan, Ogden, Salt Lake City and Provo. Officials warn people to stay off and away from slopes steeper than 30 degrees.
“Recent heavy snow combined with strong wind is creating widespread areas of unstable snow,” the Utah Avalanche Center said.