Wind slabs should be on your radar, but there's a much bigger problem in the snowpack. Choose conservative terrain to avoid the consequences of triggering a destructive persistent slab.
A bit of new snow and southeast wind should form small new slabs, but also obscure 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 have been limited. If you are heading into the mountains, please post a Mountain Information Network report!
Light flurries will add a skiff of new snow to recent wind slabs and hard wind-pressed surfaces in exposed terrain from recent strong winds. Softer snow may still be found in sheltered areas or faceting northerly aspects. If the wind lets it accumulate, the new snow will bury 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.
Friday Night
Mainly cloudy with flurries in the south of the region bringing less than 5 cm of new snow. 20 to 40 km/h southeast ridgetop wind. Treeline temperature around -5 °C.
Saturday
Still cloudy with flurries in the south of the region bringing about 2 cm of new snow. 30 km/h southeast ridgetop wind. Treeline high temperature -3 °C.
Sunday
Becoming a mix of sun and cloud with easing flurries bringing up to 5 cm of new snow. 20 to 30 km/h southeast ridgetop wind. Treeline high temperature -2 °C.
Monday
Cloudy again with flurries bringing about 5 cm of new snow. 15 to 30 km/h east ridgetop wind, easing. Treeline high temperature 0 °C.
More details can be found in the Mountain Weather Forecast.
