The avalanche failed on the layer of near-surface facets that was buried and preserved on the night of 2-11. Since 2-11, we have received 13 inches of snow at roughly 1.2 inches of snow water equivalent. Strong to extreme winds blew from the south and southwest on 2-17 and 2-18. On 2-17, I observed recently formed hard slabs at 1F density and 2 feet deep in the Horse Creek Chutes. I experienced an audible collapse and shooting cracks very close to the site of this avalanche. On 2-18, I noted these slabs are growing in size due to continued drifting. While stomping around the ridge today (2-19), the weak layer collapsed and resulted in a deep avalanche that ultimately stepped down to the ground.
Maximum depth at the crown is four feet, average depth at the crown is about 2 feet.
HS-ASc-R2-D3
Eric and I were stomping around on this ridge because we knew it held hard wind slabs on top of facets. I was very careful to probe the snow with my ski pole to find the edge of the slab. I did not want to get out on it. Once I found the uphill edge of the slab, I gave a few good stomps and the slope collapsed below me. A foot or two further downslope could have been a much different result, this is why we don't recommend getting close to the edge and trying to intentionally trigger avalanches.
