Vail & Summit County

Avalanche

Andrew McWilliams · Dec 10, 2022 · Vail & Summit County

Weather

Clear skies to start with a few clouds by noon. Temperatures started out in the single digits, but with light SW winds and ample sunshine, it quickly warmed into the 20s.

Snowpack

Below treeline snow coverage was still very thin below 10,500ft (~30cm) however last week's snow has started to build a more equally distributed base of snow at lower elevations. From about 11,000 to 11,500 the height of snow was between 45cm and 60cm. There was lots of collapsing on SE aspects near and below treeline, especially where snow heights were higher. The newer snow was resting on a 3cm melt-freeze crust above faceted snow to the ground. As I moved higher in elevation, collapses became less frequent, but louder and larger. Near treeline on an east aspect, I observed a natural R1D1 into the old snow. When I approached a similar slope, the whole thing collapsed and cracked, but did not avalanche. I dropped a medium-sized cornice onto this slope with only a loose dry result in the new snow where the cornice fell. This was a great example of the stiffening slab that is giving fewer obvious signs of instability. I am sure that had I skied that slope, it would have avalanched. On my egress, southerly aspects were supportable to skis on the melt-freeze crust. On easterly aspects, I was supported in some places by the old wind slab, but in others my skis penetrated into the old snow. The snow was warming southerly aspects as I skied out and it's likely these became moist by days end.

Avalanche

Lots of cracking and collapsing on east to southeast aspects near and below treeline. There was an older natural avalanche likely from earlier in the week on an east aspect near treeline - R1D1.