Avalanche Forecast

Cold, Arctic air and north winds take the reins

Saturday night: Decreasing cloudiness, isolated flurries with trace accumulations, winds becoming north and decreasing to light, treeline low temperatures near -22 C.

Sunday: Mix of sun and cloud, no new snow expected, light northeast winds, treeline high temperatures near -20 C.

Monday: Sunny in the morning, cloudy by the afternoon, no new snow expected, winds becoming northwest and increasing to moderate, treeline high temperatures near -18 C.

Tuesday: Mainly clear, no new snow expected, moderate north winds gusting strong at higher elevations, treeline high temperatures near -15 C.

It remains possible to trigger to wind slab avalanches on Sunday, especially near ridge crests and roll-overs. Cornice falls and wind slab avalanches have the potential to step-down to deeper layers, triggering large, destructive avalanches. 

Since Thursday, operators have reported numerous large (up to size 2.5) explosive-triggered avalanches releasing in the storm snow on a variety of aspects. Additionally, several large (up to size 2) cornices have been both human-triggered and explosive-triggered. 

On Friday, a large (size 2.5) persistent slab avalanche was skier-triggered in the backcountry near Blackcomb. It released around 110 cm deep on the early December crust layer on a northwest facing slope around 2100 m in a shallow rocky start zone. Last week's forecaster blog is still relevant.

Over the past week, the mountains picked up 45-90 cm of new snow, with the final 10-20 cm coming in very cold and light. Strong south winds have had an ample supply snow to drift into reactive slabs on leeward slopes, and cornices may be reaching their breaking point. Winds are forecast to shift to the north and decrease to light, which may have the potential to create an unusual cross-loading or reverse-loading pattern in wind-exposed areas.

Start simple and gather information as you go. Monitor for changing slab conditions as you move into wind-exposed terrain and assess the bond of the new and old snow interface. Seek out softer conditions in wind-sheltered areas. 

A concerning weak layer of facets (sugary snow) can be found over a widespread crust that formed in early December (down 100-200 cm). This layer has been most reactive at treeline and low alpine elevations, between 1500-2100 m. Large size 2 and 3 avalanches on this persistent slab problem have been reported recently. This problem is particularly hard to predict and tricky to manage. Get more details and photos in our forecaster blog. 

• Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
• Be especially cautious near rock outcroppings, on steep convexities and anywhere the snowpack feels thinner than average.
• Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.