Vail & Summit County
AvalancheJason Konigsberg · Dec 16, 2017 · Vail & Summit County
Weather
Cloud cover thinned as the day progressed with filtered sunshine by afternoon. Although there were light to moderate winds, no wind loading was observed.
Snowpack
Recent west to northwest winds deposited a hard slab of snow over a weak mid-pack faceted layer on easterly slopes. In the short-term it will be possible to trigger relatively small avalanches in recently wind-loaded areas. For the longer term- the east-facing slopes don't have the incredibly poor structure that northerly-facing slopes do. There are weak layers of concern, as stated above, but the weak layers are small-grained facets (not depth hoar) and are relatively stronger than there northerly counterparts. Regardless, a persistent slab structure exists and we will have to monitor east-facing slopes. Melt-freeze crusts on easterly ATL slopes were thin to non-existent. Stability tests on ATL east = ECTP12 and PST END 15/100 ---North-facing slopes ATL are completely ravaged from the last wind event.----See snowpit and video for more details.
Avalanche
The east-facing snowpit in this observation is from near a recent previously reported natural avalanche near the Breck ski area reported by patrol. The avalanche was on an east-facing above treeline slope and occurred during intense wind loading on 12/15/17.