Assess for wind slabs in steep terrain prior to committing.
Wind slabs may be found at higher elevations, particularly in steep terrain adjacent to ridgelines. Slabs may be particularly touchy where they sit on a weak layer of surface hoar crystals.
Weak, sugary faceted grains exist near the base of the snowpack. Riders are most likely to trigger this layer in steep, rocky slopes where the snowpack is inherently thin. The likelihood of avalanche activity on this layer will increase during periods of rapid change to the snowpack, such as heavy snowfall, rain, or extensive warming. Cornices are also very large at this time of year and a cornice failure could trigger this layer.
A few storm slab avalanches were reported on Tuesday. A large load remotely triggered a large (size 2.5) avalanche, which occurred within the 20 cm of storm snow that has accumulated since the weekend. Otherwise, the storm snow was sluffing in steep terrain, particularly where it overlies a hard crust on sun-exposed slopes.
Looking forward, progressive snowfall with southwest wind could continue to form slabs that could be touchy to riders.
Around 15 to 25 cm of snow overlies large (10 mm) surface hoar crystals in terrain sheltered from the wind, wind-affected snow in wind exposed terrain, and a hard melt-freeze crust on sun-exposed slopes. Strong southwest wind means that the deepest deposits are likely found in lee terrain features near ridges.
The middle of the snowpack is strong and contains numerous hard crusts.
The lower snowpack is composed of weak basal facets. The layer is currently dormant but it may become active with any rapid change to the snowpack, such as rapid loading (e.g., heavy snowfall or rain) or prolonged and extensive warming. Avoiding thin and rocky slopes is still recommended. Cornices are also very large and a cornice failure could trigger this basal layer.
Wednesday Night
Cloudy with light snowfall, accumulation 1 to 3 cm, 30 to 40 km/h southwest wind, treeline temperature -8 °C.
Thursday
Cloudy with light snowfall, accumulation 1 to 3 cm, 20 km/h southwest wind, treeline temperature -6 °C, freezing level rising to 1000 m.
FridayMix of sun and cloud with no precipitation, 30 km/h southeast wind, treeline temperature -4 °C, freezing level 1100 m.
SaturdayMix of sun and cloud with no precipitation, 30 km/h southeast wind, treeline temperature -3 °C, freezing level 1200 m.
More details can be found in the Mountain Weather Forecast.
