Avalanche Forecast
Regions: East Purcell, Purcells.
Choose sheltered, low-consequence terrain. Recently formed wind slabs in combination with buried weak layers necessitate a conservative approach.
Confidence
Moderate
Avalanche Summary
On Wednesday after the storm, a few natural wind slabs were observed in the alpine (size 1-2). Observations were limited by poor visibility.
Looking forward to Friday, wind slabs may remain reactive to human triggering at upper elevations. Concern for buried weak layers continues to warrant conservative terrain selection. This means choosing small, low-consequence slopes.
Snowpack Summary
In the past few days, up to 20 cm of new snow fell, accompanied by southwest winds, creating wind slabs and scoured surfaces at alpine and treeline elevations.
The mid-snowpack may hold a weak layer of surface hoar or facets 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
Thursday Night
Cloudy with up to 3 cm of snow. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -7 °C.
Friday
Cloudy with up to 1 cm of snow. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -4 °C.
Saturday
A mix of sun and cloud with isolated flurries. 10 to 30 km/h southwest ridgetop wind. Treeline temperature -3 °C.
Sunday
Mostly sunny. 10 to 40 km/h southwest ridgetop wind. Treeline temperature -3 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- 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
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: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1 - 2.5