We were traveling just under the ridge on the Mill B South side between Room of Doom and Santiago slightly before noon. The third skier was traversing across a small open slope when the snow broke under his feet. He was carried about 15 feet but was able to self arrest by grabbing a tree. The slide triggered adjacent slopes all the way down the ridge. Shortly before this, a large cornice had fallen into the Mineral Fork side of the ridge but did not trigger a slide.

It appears the slide failed on the interface between the most recent storm's snow and the crust that developed during the warm temps we had late last week.