Watch for wind slabs in lee features like ridge crests and steep roll-overs at alpine and treeline elevations.
A bit of new snow and wind will further wind slab development in lee features at alpine and treeline elevations. Recent winds have varied in direction so wind slabs can be found on a variety of aspects. Be mindful that wind slab avalanches can serve as triggers for deeper weak layers, resulting in large and destructive avalanches.
Thursday night: Around 5 cm new snow, up to 15 cm for the Coquihalla. Winds strong west. Freezing level 600 m.
Friday: A trace of new snow, up to 10 cm for Allison Pass. Winds moderate southwest. Freezing level 1000 m.
Saturday: Flurries. Winds strong easing to moderate southwest. Freezing level 1200 m.
Sunday: Flurries. Winds light to moderate southwest. Freezing level 900 m.
Natural wind slab avalanches up to size 2 were observed on steep, north to east facing alpine terrain on Tuesday.
On Wednesday, two cases of wind slab avalanches stepping down to deep persistent layers were reported: one was skier triggered from a thin spot in an aggressive north facing alpine feature (link to MIN report), the other a natural size 2.5 on a convex southeast aspect in an open area around treeline. In the neighbouring Sea to Sky region, a very large (size 3.5) avalanche occurred on Sunday near Whistler on a steep north face at 2400 m. These avalanches are suspected to have failed on a layer of facets on a crust from late November. These events demonstrate the ongoing need for caution in aggressive terrain, particularly in areas where deep instabilities remain.
A bit of new snow and wind will further wind slab development in lee features at alpine and upper treeline elevations. Recent winds have varied in direction so wind slabs can be found on a variety of aspects. A rain crust sits below recent storm snow below 1900 m.
In the north part of the region (ie. Goldbridge/Duffey/Hurley), a few deep instabilities exist in the snowpack, including a weak basal facet crust complex. Sporadic avalanche activity on these layers keep them on our radar.
In the south of the region, including the Coquihalla and Manning areas, we currently have no concerns about deeply buried weak layers.
