Avalanche Forecast

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Friday Overnight: Mainly clear in the evening, cloud cover increasing overnight. Northwest winds shifting southwest in the early morning and strengthening into the strong to extreme range. Light flurries possible in the early morning.

Saturday: Snowing throughout the day, 10-25 cm of accumulation. Strong to extreme southwest winds with alpine temperatures rising to around -8 C. Continued snowfall overnight with another 10-20 cm of accumulation. 

Sunday: Overnight, winds decreasing light to moderate and shifting to the west. Mainly cloudy with flurries in the morning. Alpine temperatures around -10 C. 

Monday: Partially cloudy with isolated flurries. Light southwest winds increasing moderate to strong in the afternoon. Alpine temperatures around -10 C. 

On Friday, operators in the eastern Purcells triggered several persistent slab avalanches on the early December crust up to size 2.5 on a NW aspect in the alpine with explosive control. They also triggered one size 2 deep persistent avalanche with explosives on a N aspect in the alpine.

On Wednesday, avalanche control triggered a very large (size 3) avalanche on a northwest aspect around 2050 m that released on the early December weak layer. 

On Tuesday, a large (size 2) avalanche was remotely-triggered on this same layer by a skier. This occurred on a west aspect near 2100 m and broke 100 cm deep. 

This week, 40 cm of snow has accumulated with another 10-20 cm expected throughout the day today. With a considerable amount of snow available for transport, strong southwest winds will redistribute this week's new snow into fresh, reactive wind slabs in the alpine and treeline. 

Below this new snow, consolidated snow from the previous weekend storm sits over a substantial crust that formed in early December. This crust is 10-40 cm thick and can be found down 60-100 cm. It is present across aspects below 2300m. A thin layer of weak facets (sugary snow) can found above this crust that has demonstrated reactivity in snowpack tests and recent avalanche activity. 

A late October facet/crust layer of concern sits at the bottom of the snowpack above 1900m. Although this layer has been trending less reactive, it remains on our radar.

The snowpack depth at treeline is around 115-200 cm. The deepest snowpack can be found near the Bugaboos. 

• Wind slabs are most reactive during their formation.
• Be aware of the potential for large avalanches due to the presence of a persistent slab.
• Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
• In times of uncertainty conservative terrain choices are our best defense.