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California's deadliest avalanche on record highlights Lake Tahoe backcountry skiing dangers

An avalanche north of Lake Tahoe in Northern California claimed the lives of several backcountry skiers this week.Fifteen people — four ski guides and 11 clients — were returning from a three-day touring trip to Frog Lake on Tuesday when they were caught in the avalanche at Nevada County's Castle Peak, according to Blackbird Mountain Guides, the company that organized the trip.Six of those people were able to get out of the snow and contact first responders so they could be rescued. Eight of the remaining nine have since been found dead, while the ninth person is presumed dead, law enforcement officials said.The Castle Peak avalanche was only about a mile from a slide that killed a snowmobiler back on January 5. So what makes this remote terrain so dangerous yet so enticing for skiers and riders?Every winter, Donner Summit, the area of the Sierra Nevada mountain range where Castle Peak is located, receives an average of 411.5 inches of snow annually, which makes Frog Lake one of the snowiest places in the western hemisphere, according to the Truckee Donner Land Trust.Frog Lake sits at 7,600 feet. It's a miles-long journey from the trailhead, with an elevation gain of more than 1,000 feet. Snowcats, snowmobiles, or hiking are the most common ways skiers and riders access this rugged backcountry zone, and it's critical to have the proper equipment and safety gear. Experts suggest wearing proper avalanche gear, such as beacons, probes, and shovels, and carrying satellite phones in case of an emergency.

There is no avalanche mitigation in the area where Tuesday's avalanche occurred, and in the wilderness, risks always exist – especially in the blizzard conditions the Sierra has experienced this week.The Nevada County Sheriff's Office said they are questioning the touring company and are working to learn more about the group's decision to head into the backcountry during this predicted storm cycle.Tuesday's avalanche was the fourth-deadliest in U.S. history, and the deadliest in California history.