Continued high freezing levels and precipitation are keeping the hazard elevated. An increased load on our weak snowpack makes natural avalanches likely. Avoid all avalanche terrain.
Cornices are large, looming, and becoming weak with warm temperatures and precipitation. A large cornice fall can be dangerous on its own, and can also trigger deep slabs on slopes below.
Several persistent weak layers exist in the upper meter of the snowpack. With freezing levels remaining high and forecasted precipitation, these layers may fail naturally, producing very large and destructive avalanches.
Mixed precipitation with snow above 2000 m accumulating late in the day Thursday will develop storm slabs that are forming over a moist surface. Storm slabs will be more reactive where wind has accompanied the storm.
Widespread large natural avalanche activity continued Tuesday, including wet loose to size 2 and storm & persistent slabs to size 4.
Large, destructive, persistent slab avalanche activity is expected to continue with incoming precipitation before the freezing levels begin to lower Thursday afternoon.
Mixed precipitation of rain switching to snow will further saturate the upper snowpack, adding to a moist to wet upper snowpack that sits over a crust. Below lies a complex snowpack with several weak layers, which are currently a concern for triggering persistent slab avalanches:
Facets/surface hoar/crust from early March buried 40 to 60 cm deep,
Facets/surface hoar/crust from mid-February buried 110 to 130 cm deep, and
Facets/surface hoar/crust from late January buried 120 to 160 cm deep.
This complex snowpack, combined with high freezing levels and precipitation, makes travel in avalanche terrain dangerous.
Wednesday night
Cloudy. Rain showers. 20 to 40 km/h south ridgetop wind. Treeline temperature 0 °C. Freezing level 2200 m.
Thursday
Cloudy, rain continues below 2000 m, 10 to 20 cm of snow. 20 to 30 km/h variable ridgetop wind. Treeline temperature 0 °C. Freezing level falling to 2000 m.
Friday
Cloudy, flurries, 5 to 10 cm. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -1 °C. Freezing level falling to 1500 m.
Saturday
Cloudy, 5 to 10 cm of snow. 15 to 20 km/h west ridgetop wind. Treeline temperature -1 °C. Freezing level 1500 m.
More details can be found in the Mountain Weather Forecast.
