Sun and daytime warming can quickly change snow conditions. Avoid steep slopes if the snow is moist, and stay well clear of cornices, which may weaken and threaten slopes below.
A persistent weak layer of faceted snow surrounding a firm crust is buried 100 to 200 cm deep. While difficult to trigger, large loads—such as a cornice falling onto the slope below have proved to trigger this layer.
Watch for surface snow becoming moist and back off steep slopes while solar radiation is intense.
On Thursday, the NW Field Team saw a natural size 3 persistent slab in the alpine on a west aspect. They suspect it was up to 24 hrs old.
On Wednesday, reports of steep sun-facing slopes shed small wet loose avalanches up to size 1.
On Tuesday, a large, size two avalanche was triggered by a snowmobile. The release was in an open alpine feature and may have involved a weak layer down 75 to 150 cm.
Sunny skies, daytime warming and continued northwest winds have created variable surface conditions. In the alpine, isolated pockets of wind slab may exist on northerly slopes. Melt-freeze conditions exist on sun-facing slopes.
At treeline and below, moist and/or refrozen surfaces exist on sunny slopes, and dry snow (up to 10 cm) may be found on northerly slopes. Below 700 m, the snowpack is becoming isothermal. On sun-facing slopes, the surface snow is moist.
A thick crust with faceted snow from late January can be found at a wide range of depths, from 75 to 150 cm. A cornice fall (large load) may be enough to trigger this slab.
Friday Night
Mostly clear skies. 10 km/h southwest ridgetop wind. Treeline temperature 2 °C. Freezing level 1700 m.
Saturday
Mostly cloudy. 10 km/h east ridgetop wind. Treeline temperature 1 °C. Freezing level 1600 m.
Sunday
Mix of sun and clouds. 10 km/h south ridgetop wind. Treeline temperature 1 °C. Freezing level 1500 m.
Monday
Mix of sun and clouds. 3 mm of precipitation as snow or rain at treeline. 40 km/h southwest ridgetop wind. Treeline temperature 1 °C. Freezing level 1500 m.
More details can be found in the Mountain Weather Forecast.
