- Location: Near Lindley Hut, south of Ashcroft
- State: Colorado
- Date: 2019/01/11
- Summary Description: 2 backcountry tourers caught, 1 partially buried, 1 partially buried-critical
- Primary Activity: Backcountry Tourer
- Primary Travel Mode: Ski
- Location Setting: --
- Caught: 2
- Partially Buried, Non-Critical: 1
- Partially Buried, Critical: 1
- Fully Buried: 0
- Injured: 0
- Killed: 0
- Type: SS
- Trigger: AS - Skier
- Trigger (subcode): r - A remote avalanche released by the indicated trigger
- Size - Relative to Path: R2
- Size - Destructive Force: D2
- Sliding Surface: I - New/Old Interface
- Slope Aspect: NW
- Site Elevation: 10800 ft
- Slope Angle: 39 °
- Slope Characteristic: Convex Slope,Concave Slope
This was a soft slab avalanche remotely triggered by a skier from the bottom of the slope. The avalanche was small-sized relative to the path, and had the destructive force to bury, injure, or kill a person (SS-ASr-R2-D2-I). It broke approximately 2 feet deep on a buried layer of near-surface facets that developed between storms in mid-December. The avalanche broke approximately 150 feet wide and ran around 200 vertical feet. The avalanche released on a northwest-facing slope around 39 degrees in steepness at an elevation around 10,800 feet.
The new year started with 3 to 5 inches of snowfall on January 1. There was a short dry spell before a more potent storm arrived January 6 to 7, depositing around 6 inches of snow at the Lindley Hut. This storm came in with strong southwest winds. From January 8 through January 10 there was periodic light snowfall with little accumulation. Winds were light from southwest with daytime highs in the 20s and nighttime lows in the teens. Five inches of new snow fell overnight on January 10 and the morning hours of January 11 with light northwest winds.
October snowfall faceted during dry weather in the first two weeks of November. Slopes that face north and east above about 10,500 feet in elevation held the most early season snow. November storms built soft slabs on these basal weak layers. A layer of near-surface facets formed during a sustained dry period during the middle of December. This persistent weak layer was persevered and buried by a larger storm event around Christmas. Additional storms arrived around New Year's Day and again on January 6 to 7. The latter of these storms caused a widespread natural avalanche cycle. The buried near-surface facet layer was the culprit weak layer for many of these avalanches. The avalanche in this incident broke on the same weak layer.
Two skiers (part of larger group staying at the Lindley Hut) were caught in debris from a single event that released two avalanches. One skier initially triggered a small sluff in the faceted snow, which knocked both skiers over. The initial sluff then triggered a soft slab that broke approximately 100 feet above the two skiers. The slab continued to fracture 150 feet further up the hill, along the leeward, north side of the small ridge. The top portion of the crown was in a small concave bowl near the steepest part of the ridge. The slab avalanche at its widest point was roughly 150 feet wide, averaging two feet deep and ran approximately 200 vertical feet.
The debris from the slab avalanche washed both skiers into trees. Skier 1 was partly buried to his chest, and Skier 2 was partly buried-critical, with only the top of one arm visible. Skier 1 was able to self-extricate, and then quickly dig deep enough with his hands to expose a clear airway for Skier 2. Skier 1, with the help of others who arrived on scene, extricated Skier 2. Both skiers were uninjured and recovered all their gear.
This slope is the site of two previous fatal avalanche accidents, in February 2010 and March 2002.
Figure 5: Snow profile near the flanks of the avalanches. Jan 11, 2019.