Avalanche Forecast
Regions: East Purcell, Purcells, West Purcell.
Choose sheltered, low-consequence terrain. Recently formed wind slabs in combination with buried weak layers necessitate a conservative approach.
Confidence
Moderate
Avalanche Summary
A natural avalanche cycle took place during the storm last Wednesday.
On Thursday, explosive control in the Invermere area produced two size 2 deep slab avalanches from east-facing treeline terrain.
On Friday, one size 1 natural slab avalanche was observed from afar on a north aspect at 2600 m.
Snowpack Summary
Light overnight falls atop 20 cm of recent storm snow with deeper deposits accumulating in lee-facing terrain at higher elevations due to southwest winds.
The mid-snowpack may hold a weak surface hoar or facets layer on shaded slopes and a sun crust on south-facing slopes, buried 20–40 cm deep.
Near Invermere, the snowpack base is weak, with faceted snow over an October crust. This layer likely exists region-wide but has only shown signs of instability near Invermere.
Weather Summary
Saturday Night
Cloudy with up to 5 cm of new snow. 10 to 40 km/h southwest ridgetop wind. Treeline temperature -4 °C.
Sunday
Cloudy with up to 1 cm of new snow. 15 to 30 km/h southwest ridgetop wind. Treeline temperature -5 °C.
Monday
Cloudy with up to 3 cm of new snow. 15 to 30 km/h southwest ridgetop wind. Treeline temperature -4 °C.
Tuesday
Cloudy with up to 2 cm of new snow. 20 to 50 km/h southwest ridgetop wind. Treeline temperature -3 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Wind Slabs
Recently formed wind slabs may remain reactive to human triggering at upper elevations.
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
Expected Size: 1 - 1.5
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: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1 - 2.5