This is a human triggered avalanche that happened at the currently closed ski area of Alta. The ski area is not doing any avalanche control and you must treat the terrain within the boundaries as backcountry. Details are a bit vague but it appears a party of two triggered it from the ridge and were not caught.

The slide was originally viewed from a distance on Thursday by Craig Gordon with only speculation on actual size and weak layer. On Friday Brett Kobernik walked up to look at it up close. The weakness became very obvious at that point. The slide was around 200’ wide. The starting zone was in the 10,400 to 10,800' range.

Another view with Main chute as well.

The largest portion of the crown face measured 33" deep. Account for the rapid settling yesterday and today and it may have been just over 3' deep.

It averaged 14 to 20” deep. The slab was a stiff wind deposited layer from the last storm. The weakness was small grained faceted snow that formed from previous snowfall earlier in October. No melt freeze crusts were present at this elevation. The melt freeze crusts currently deeper in the snowpack disappear at around 10,200’ and higher on north facing slopes.

The average slope angle was right in the 38 degree zone. The avalanche traveled around 1000’ vertical feet. This slide could have been triggered remotely from the ridge as the party was ascending a safe route. Faceted snow being the weak layer could support this theory.

This is looking into Main Chute off the top of Baldy. It naturally avalanched near the end of the last storm. You can be sure that small grained facets were the culprit as well as a decent wind load.