Avalanche Forecast
Regions: Dogtooth, East Purcell, Esplanade, Purcells, West Purcell.
Use extra caution at higher elevations with shallow snowpack, especially where the buried crust is breakable. A tricky layer of surface hoar is continuing to produce large avalanches.
Confidence
Moderate
Avalanche Summary
Since Monday, large skier-triggered avalanches (up to size 2,5) have been reported in the Esplanade and Dogtooth Ranges, with some being remotely triggered. They all occurred between 2100 m and 2400 m on alpine slopes and ran on the concerning surface hoar layer 40-60 cm deep. Small wind slab were also reactive to skier traffic on Thursday. If you go out in the backcountry, please consider sharing your observations on the Mountain Information Network (MIN).
Snowpack Summary
The total of recent snow is up 20-30 cm throughout the region. Moderate to strong westerly winds have redistributed into deep pockets in lees at higher elevations. This overlies a variety of old layers including a surface hoar layer, sun crust, and wind-affected snow.
A prominent rain crust is found 40 to 60 cm deep and has been reported to extend as high as 2300 m around Invermere and 2000 m around Golden. A layer of surface hoar is also found at this depth and is a particular concern in areas without a thick crust.
The lower snowpack contains large, weak snow grains and in some places a hard crust near the ground. Typical snowpack depths at treeline are 60 to 110 cm, and taper rapidly below treeline.
Weather Summary
Thursday Night
Cloudy with isolated flurries, trace accumulation, alpine wind southwest 30 to 40 km/h, treeline temperature -3 °C, freezing level at 1700 m.
Friday
Cloudy, 2-4 cm of snow, alpine wind southwest 40 to 50 km/h, treeline temperature -3 °C, freezing level at 1700 m.
Saturday
Mix of sun and clouds, no precipitation, alpine wind northwest 30 to 40 km/h, treeline temperature -10 C, freezing level at 800 m.
Sunday
Mix of sun and clouds, no precipitation, alpine wind southwest 30 to 40 km/h, treeline temperature -8° C, freezing level at 800 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Wind Slabs
Human-triggered wind slab avalanches are likely on leeward terrain features such as ridge crests and roll-overs in the alpine. Be especially cautious as you transition into wind-affected terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1.5
Persistent Slabs
Choose terrain assuming the weak layers capable of producing large avalanches. The layers of concern are a surface hoar layer buried 40 to 60 cm deep and weak facets at the base of the snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5