2011/02/22 - Colorado - East Snowmass Creek Valley, Sand's Chute

Published 2011/02/27 by Brian McCall - Forecaster, CAIC

CAIC staff were unable to access the site to gather snowpack information. Continued wind loading during the days after the accident triggered additional natural avalanches and kept the avalanche danger at Considerable (Level 3). Interviews with the group members indicate that the avalanche likely broke in weak layers of faceted snow or depth hoar in the middle or lower portions of the snowpack. These weak layers sat below multiple layers of wind slabs that had been deposited in the upper snowpack during the previous month. In the two weeks prior to this accident, snow storms and strong winds built new layers of snow that increased the load on weaker layers deep in the snowpack. During the same time period there were both natural and human triggered avalanches in the Aspen zone. Most of these avalanches released on buried layers of surface hoar, small facets and depth hoar.

The group of skiers involved in this accident were very familiar with the terrain in the East Snowmass Creek valley. They had traveled in that area many times this season and during the previous four or five winters. Two members of the group skied a run in the west and northwest facing terrain of Fool's Chute earlier in day without incident. This is an off piste area just south of the terrain that would slide later in the afternoon. After this first lap, the group returned to the ski area and picked up another friend who joined them for the afternoon. The three then headed out of bounds and skied a second run, also in west and northwest facing terrain near treeline. Their third lap of the day was in Sand's Chute. They started this run around 2pm. During this day in the backcountry, they noted one recent natural avalanche that occurred on an east aspect across the valley just below treeline. They had observed the wind transport that was occurring starting late morning. They did not dig any snow pits on the day of the accident. This group had dug snow pits in this area on trips earlier in the year.

Once in Sand's Chute, the group skied one at a time. Since they had observed blowing snow, they expected any avalanches to be small, shallow wind slabs. They did not expect avalanches to break into deeper snowpack layers. The first skier descended and pulled out into a safe zone. The second skier entered the path and triggered the avalanche on approximately his third turn. He was caught, carried, and fully buried in the avalanche.

Skier number one watched the avalanche pass from his safe zone near the bottom of the steep chute. Once it stopped, he switched his avalanche beacon to receive and skied down the debris. Due to the narrow track of the avalanche path in this gully, he was able to ski straight down the fall line quickly and find a signal of his buried partner almost immediately. He hit the victim with a probe within 1-2 minutes. The victim's head was uncovered within about 5 minutes. Skier number three made his way down a ridge to the left of the avalanche and was able to assist with the digging. They performed CPR for about 30-35 minutes with no results. The survivors then skied out of the valley and were able to make a phone call for help from a restaurant located in the upper part of Snowmass Village.

Strong southwest winds, recent new snow available for transport, and weak layers in the lower snowpack were all contributing factors to both the accident and the cycle of natural avalanches occurring that day. Near the time of this accident a large natural avalanche ran on a wind loaded northeast aspect above treeline on Garret Peak on the opposite side of the valley. This avalanche traveled full track reaching the valley floor, approximately 2600 vertical feet below. The debris reached the creek just up valley from Sand's Chute. Due to the complex and exposed terrain and the risk of further avalanche activity, efforts to recover the victim's body have been delayed until snow stability improves.