Vail & Summit County

Avalanche

Anonymous · Nov 21, 2021 · Vail & Summit County

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Weather

At the base of the couloir (Easterly aspect, 12,500'), it felt like spring. The temperature was 30 F and there was no wind. The bottom was in the sun from sunrise to noon. At the top of the route (easterly aspect, 13,000'), winter like conditions were encountered. The temperature was lower and the wind was blowing between 15-20 mph.

Snowpack

The snowpack varied greatly based on aspect. The eastern aspects held deep wind drifts, while the western sides were completely windswept. On 16 October, I observed that the couloir was completely filled in while ice climbing across the valley. On the morning of 21 November, the mountains had significantly more snow. At the Blue Lakes trailhead, there was 2" of new snow on previously bare ground. At the base of the route at 12,500' (easterly aspect), the snowpack was 240 cm deep with 15 cm of fresh snow on top. The old snow was extremely well consolidated, pencil hardness, to the ground. A compression test yielded no failures. When booting up the couloir similar conditions appeared to exist at the base. The was about 6" of fresh snow on a consolidated base. There were pockets of deeper wind blown snow, but it had not formed into a wind slab. The top 20' of the couloir had a different snowpack than the rest. The snowpack was mad up of small facets with a 1-3" wind slab on top.

Avalanche

A small crack in the 2" thick wind slab was noted when we topped out. After transitioning at the top of the line, my partner dropped in first. He made 2 hard turns before going over a steep convex roller where the crack in the wind slab was previously seen. On his 3rd turn just below the roller, the slope fractured above him. It broke at the apex of the rollover on the older snow surface. It broke 30' wide and the crown was between 6" and 12". The avalanche carried my partner 20' before he was able to escape behind a rock outcropping. He was uninjured. The avalanche continued to run for 700' before stopping in the partially covered boulder field.