Choosing moderate-angled slopes with thick, uniform snowpack coverage is a good way to avoid triggering both wind slabs and the much more destructive weak layer deeper in the snowpack.
Light new snow amounts and southeast wind has likely formed small new slabs, but also obscured older slabs lingering in the alpine. If triggered, wind slabs may step down to deeper layers, causing large, destructive avalanches.
A layer of facets over a crust is buried 80 to 150cm, and has recently produced very large avalanches. It appears to be most reactive in areas closer to the coast.
Last Saturday, a skier-triggered size 2 persistent slab was reported on the US side of the border. This avalanche occurred on a northwest aspect at approximately 1500 m and ran on the mid-February layer. This layer is a concern on the Canadian side as well.
We suspect that avalanche activity has been tapering over the past few days, but observations are very limited. If you are heading into the mountains, please post a Mountain Information Network report!
About 5 cm of new snow has buried or combined with recent wind slabs and hard wind-pressed surfaces in exposed terrain while adding to softer snow in sheltered areas or faceting northerly aspects. If the wind let it accumulate, it buried sun crust on or near the surface of sun-exposed slopes.
A persistent weak layer of facets and crust is buried 80 to 150 cm deep, extending up to about 1400 m. The greatest concern for triggering comes from large loads, such as cornice falls, or from human triggering in areas where the snowpack transitions from thin to thick. This layer appears most reactive closer to the coast, with decreasing reactivity farther inland.
Saturday Night
Cloudy with isolated flurries and a trace of new snow. 20 km/h south ridgetop wind. Treeline temperature -5 °C.
Sunday
Cloudy with isolated flurries and a trace of new snow. 20 km/h southeast ridgetop wind. Treeline high temperature -3 °C.
Monday
Mostly cloudy with flurries continuing from overnight bringing up to 5 total cm of new snow. 20 to 40 km/h east ridgetop wind, easing. Treeline high temperature 0 °C.
Tuesday
A mix of sun and cloud. 20 km/h west ridgetop wind. Treeline high temperature -2 °C.
More details can be found in the Mountain Weather Forecast.
