Observation Date: 01/31/2014

Route/Location:
Backside of Lost Trail ski area. SS-ASu-R1-D1.5-I

Weather:
Cloudy with Light to Moderate Snow most of the day with Calm below ridgeline with Light NW winds at ridgeline. Some blowing snow. Probably picked up an inch or two of very light density snow.

Wind:
Light NW winds at ridgelines. Some blowing snow. New snow available for transport.

New Snow: 3-6″

Snow Density:

Avalanche Activity:
SS-ASu-R1-D1.5-I Skier triggered on a NE-E facing aspect on a 36-37* slope at around 7000′. Slab broke down 40-50cm deep at the old/new snow layer. Near Surface Facets and some buried surface hoar are the suspected culprits. It was interesting to note a super fine, barely perceptible melt/freeze crust had formed on top of the facets/ surface hoar layer. HS- 145cm at crown. As far as we know, no one was caught or injured in this slide.

Observed Danger Rating:

Other Comments:
While our group found great skiing today, we may have been pushing the terrain a bit more than we should have, given the slide we saw at the end of our day. We saw the skier triggered slide on our last run and it was certainly a wake up call that the new snow has not bonded very well to the the old snow surface where faceting and/or buried surface hoar exists. We also found this facet layer up higher at around 7600′. While I don’t know if the surface hoar issue is widespread on non-solar/ wind protected slopes, I do believe that the near surface faceting issue is widespread on shady aspects. This slab was not very big, but could have had serious consequences of being pulled through trees. Be suspect of non-solar slopes steeper than 35* especially if rocks and/or convex rolls are present or if the consequences of even a small slide could be high. Dig down to see how the new snow is bonding to the old snow surface. Are facets present?

Observer: George D’Angelo

Layering at crown Crown and flank Overview of location of avalanche within terrian