Just days before a deadly avalanche killed eight backcountry skiers near Tahoe, the guiding company leading the trip warned on social media that unstable snowpack could trigger “unpredictable avalanches.”
Blackbird Mountain Guides posted a video Sunday on Instagram cautioning that recent snow conditions around Tahoe were creating atypical layering in the snowpack — a combination that could lead to abnormal avalanche behavior.
The company was leading 15 backcountry skiers on a three-day trek to the Frog Lake Huts when they were caught in a football field-sized avalanche Tuesday near Castle Peak.
Six people survived. Eight were killed. One skier remains missing and is presumed dead as rescue efforts shift to recovery operations amid continued storm conditions and high avalanche danger.
Three of the four guides leading the trip were among those killed.
The Instagram post, published ahead of a major winter storm expected to dump several feet of snow across the Tahoe region, warned that recent dry periods followed by new snow had created a “particularly weak layer” within the snowpack.
In the video, guides on skis dig through layers of snow at Mount Rose on the Nevada side of Tahoe, identifying what they described as a “microcrust” and a layer of “sugary weak facets.” At higher elevations, they said, the crust was “almost nonexistent.”
“This weak layer could lead to some unpredictable avalanches!” text on the screen reads as a guide sifts soft snow through his fingers.
The company explained that the snowpack was forming “atypical layering” for this point in the season.
“Typically, we’d expect small amounts of faceting between big storms, but with a crust and extended dry period for the month of January into February, faceting has been a driving force in the snowpack,” the company wrote.
That layering, the post said, resulted in a “particularly weak layer.”
“As we move into a large storm cycle this week, pay close attention to places where faceting has been particularly strong — avalanches could behave abnormally, and the hazard could last longer than normal,” the company said, urging people to “use extra caution” and monitor alerts from the Sierra Avalanche Center.
The Sierra Avalanche Center had issued an avalanche warning for the central Sierra Nevada — including the Castle Peak area — at 5 a.m. Tuesday, hours before the slide. The warning, initially set to run through early Wednesday, rated avalanche danger in the region as “high,” the second-most-dangerous level below extreme. The center later extended the warning through Wednesday.
Authorities have said severe weather has complicated efforts to determine exactly what triggered the avalanche. Nevada County Sheriff Shannan Moon said there were “great questions” about the company’s guiding decisions, though she did not elaborate.
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