Recently formed slabs will require some time to bond to the snowpack, particularly where they overly a widespread weak layer.
Storm and wind slabs have formed from 30 to 60 cm of recent snow, which will remain touchy to riders for some time. The snow sits on a widespread layer of surface hoar crystals in areas sheltered from the wind and a hard crust on sun-exposed slopes. Expect to find wind slabs in steep terrain features at high elevations.
A weak layer of faceted grains above a hard melt-freeze crust is buried around 120 to 250 cm deep. Although the likelihood of triggering this layer is expected to reduce given the current weather trend, the snowpack structure remains. Any release on this layer would be highly consequential.
TUESDAY NIGHT: Clear skies with no precipitation, 10 to 20 km/h north wind, alpine temperature -22 C.
WEDNESDAY: Increasing clouds with afternoon snowfall, accumulation 1 to 3 cm, 20 km/h southwest wind, alpine temperature -20 C.
THURSDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 20 to 40 km/h west wind, alpine temperature -12 C.
FRIDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 40 to 60 km/h southwest wind, alpine temperature -7 C.
Widespread avalanche activity was observed on Monday. They were mostly small to large (size 1 to 2.5) storm slabs, being triggered naturally, by riders, and explosives. They often failed on the surface hoar crystals described in the snowpack summary. For areas where the recent snow had not formed a cohesive slab, small loose dry avalanches were observed.
A large explosive triggered the December 1 facet/crust layer described in the snowpack summary. The avalanche was at 1600 m in an opening, on a southwest aspect. It varied from 50 to 180 cm deep.
Looking ahead to the coming days, storm slab avalanches are expected to remain triggerable by riders as the recent snow settles and forms a cohesive slab above the widespread surface hoar layer.
Around 30 to 60 cm of recent snow overlies weak surface hoar crystals 5 to 15 mm in size, which is most prominent in areas sheltered from the wind. The snow has consolidated and formed storm slabs in some areas, which is expected to remain touchy to riders for some time. In other areas, the snow remains uncohesive without slab properties. The snow overlies a melt-freeze crust on sun-exposed slopes. Expect to find wind slabs in lee terrain features at higher elevations.
A few other weak layers of surface hoar and faceted grains exist in the top metre of snow but are reported as hard to find.
The facet/crust layer that formed in early December is buried around 120 to 250 cm. The last reported avalanche was on January 31 from a large explosive, and before that on January 23. This is a low probability but high consequence problem. Check out the forecaster blog for more information.
