Avalanche Forecast
Regions: Dogtooth, East Purcell, Purcells.
Buried weak layers may become more reactive with recent snow and wind loading. Allow some time for the snowpack to stabilize before entering consequential avalanche terrain.
Confidence
Moderate
Avalanche Summary
On Tuesday, a ski cut triggered a size 1 persistent slab avalanche at 2300 m in a deeper snowpack area near the Purcell Wilderness Conservancy. This failed on the early December surface hoar down 40 cm.
On Monday, a natural size 2 avalanche was reported on an east aspect at 2300 m near Bugaboo Provincial Park. In the Dogtooth, explosives triggered a size 1 avalanche on a north aspect in the alpine which is expected to have failed on the early December weak layer.
Snowpack Summary
Roughly 10 cm of new snow fell Wednesday morning, along with moderate alpine winds.
In the mid snowpack, a weak layer of surface hoar and/or small facets is buried on shaded slopes, while a buried sun crust is found on south-facing slopes. The depths of these layers range from 30 to 50 cm (with the south of the region seeing closer to 30 cm).
Particularly around Invermere, the base of the snowpack consists of weak, faceted snow over a crust formed in late October. This layer is likely present throughout the region, though it has not yet been reported as reactive outside the Invermere area.
Weather Summary
Wednesday Night
Mostly clear. 40 km/h west ridgetop wind. Treeline temperature -8 °C.
Thursday
Mostly sunny. 20 km/h southwest ridgetop wind. Treeline temperature -5 °C.
Friday
Mix of sun and cloud. 20 km/h southwest ridgetop wind. Treeline temperature -3 °C.
Saturday
Mostly sunny. 20 km/h south ridgetop wind. Treeline temperature -3 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and slopes above cliffs.
Avalanche Problems
Wind Slabs
Watch for fresh wind slabs in exposed alpine terrain.
Wind slabs have the potential to step down to buried weak layers, resulting in larger-than-expected avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Possible - Likely
Expected Size: 1 - 1.5
Persistent Slabs
A weak layer from early December appears to be most reactive in the deeper snowpack areas including the Dogtooth and western Purcells. This layer may become increasingly reactive with recent loading from new snow and wind.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Deep Persistent Slabs
In the Invermere area, weak faceted snow at the base of the snowpack remains a concern. Avalanches have occurred on steep, smooth north-facing slopes where the snowpack is shallow and weak.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood: Unlikely
Expected Size: 1 - 2