Investigation faults guides in Tahoe avalanche that killed Tiburon skier

The guides who led Tiburon resident Kate Morse and 10 other skiers into a fatal avalanche near Lake Tahoe on Feb. 17 chose a route through a known danger zone and allowed the group to travel in numbers that multiplied their collective risk, investigators have formally concluded — findings that underpin an active criminal-negligence investigation into the Truckee-based guide company responsible for the trip.

The Sierra Avalanche Center released its report last week, six weeks after the slide killed nine people, including Morse and five other women, along with three guides from Blackbird Mountain Guides. It was the deadliest avalanche in modern California history.

“This group traveled below avalanche terrain and through the runout zone of an avalanche path during a period when a natural or human-triggered avalanche was likely to very likely,” investigators concluded.

The group’s size compounded the danger.

“Exposing only one person at a time to avalanche terrain is an accepted best practice for backcountry travel,” the report states. “This group consisted of 15 people. Analysis of past avalanche accidents has indicated that larger group sizes (four or more people) have higher chances of being caught in avalanches.”

Morse, a 45-year-old biotech executive and mother of three, was among eight close friends whose children ski for Sugar Bowl Academy near Donner Summit. Two separate touring groups — six women with two guides, and five men with two guides — had spent two nights at the Frog Lake backcountry huts near Castle Peak on a guided Presidents Day weekend trip. On the morning of the accident, the guides merged the two parties into a single group of 15 for the return to the trailhead.

By the time the avalanche struck at 11:30 a.m., the Sierra Avalanche Center had upgraded its forecast to a warning, with danger at Level 4 on a 5-point scale. Wind gusts at a nearby Palisades Tahoe chairlift — about 20 miles from the accident site — reached 125 mph. The Central Sierra Snow Lab, about 4 miles from the accident site, recorded 111 inches of snowfall during the storm. The slide ran approximately 400 vertical feet and left a debris field about 100 feet wide. Search-and-rescue crews arrived about 5:30 p.m. — roughly six hours after the slide — by which time another 2 feet of new snow had buried the debris.

Two members of the group were not caught in the avalanche. One had fallen behind while struggling with a ski binding; a guide had waited with him. The report notes the separation “may have kept them from being caught in the avalanche along with the rest of their party.” The pair dug out two of the four buried survivors; investigators concluded that quickly clearing their airways was lifesaving.

Several group members carried avalanche airbag backpacks, designed to keep a skier near the surface during a slide, but none deployed. The devices require a manual trigger and offer little protection once a person is fully buried by compacted snow.

What triggered the avalanche — the group itself or natural causes — remains undetermined.

Blackbird disputed the findings.

“The report does not reflect the full scope of what transpired and does not include all of the facts and information currently under review,” spokesperson Mary Ann Pruitt told the Associated Press. “We are cooperating fully with authorities and will share more when it is appropriate and based on verified and confirmed findings.”

The Nevada County Sheriff’s Office has opened a criminal-negligence investigation. California’s Division of Occupational Safety and Health has launched a parallel workplace-safety inquiry with six months to complete.

Investigators cautioned that their account relies heavily on statements two surviving men gave to the New York Times; both were at the rear of the group and played no role in route planning. Survivors closer to the front — including the women who managed to escape — have not yet spoken publicly.

Reach Executive Editor Kevin Hessel at 415-435-2652.