Wind slabs and persistent slabs may linger in alpine terrain.
The wind was from the north and is shifting to the south, meaning wind slabs may linger on all aspects. Assess for hard, hollow sounding snow in steep terrain before committing.
A weak layer of surface hoar and/or faceted grains around a hard crust could be triggered by riders. The layer is buried around 60 cm in the eastern portions of the region and up to 140 cm around White Pass. This layer has recently produced widely propagating avalanches in alpine terrain and it is capable of being remotely triggered from a distance. The most likely area for riders to trigger it is in wind-sheltered, north-facing terrain, and in rocky terrain where the snowpack is thin.
Riders observed evidence of old loose dry and wind slab avalanches over the weekend, predominantly starting in alpine terrain and on southerly slopes.
The latest persistent slab avalanche report was from a week ago where riders remotely triggered the layer from a ridgetop, but snowpack test results indicate this layer could still be triggered and form large avalanches.
Wind affected snow and wind slabs are found in exposed terrain, whereas soft snow may be found in wind-sheltered features, particularly at treeline elevations. The wind has predominantly been from northerly aspects but is shifting to the south, meaning wind slabs may be found on all aspects.
There is a buried layer of surface hoar about 60 cm deep in Powder Valley, Tutshi, and Paddy Peak areas and up to 140 cm around White Pass. This layer is most prominent on northerly slopes sheltered from the wind. On other aspects, this layer is a hard melt-freeze crust with weak facets around it. This layer is has been most problematic in alpine terrain.
The middle of the snowpack is consolidated and strong. Weak faceted grains are found near the base of the snowpack, which are most pronounced in thin snowpack areas.
Tuesday Night
Partly cloudy with no precipitation, 10 to 20 km/h southeast wind, treeline temperature -15 °C.
Wednesday
Mostly cloudy with light snowfall, accumulation 1 to 3 cm, 20 to 40 km/h south wind, treeline temperature -11 °C.
ThursdayCloudy with snowfall, accumulation 10 to 20 cm, 60 km/h south wind, treeline temperature -4 °C, freezing level rising to 1000 m.
FridayCloudy with snowfall then clearing, accumulation 5 to 10 cm, 40 km/h south wind, treeline temperature -4 °C.
More details can be found in the Mountain Weather Forecast.
