Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
The only way to reduce risk when dealing with the basal weak layer is avoidance, as we can't know which slopes will slide and when. Factor this into your terrain choices.
Confidence
Moderate
Avalanche Summary
A large deep release was reported out of the north side of Surprise Pass on Tuesday, and Sunshine ski Hill reported a natural size 3 deep persistent avalanche in the backcountry on the Monarch.
Snowpack Summary
15-40 cm of snow in past week (most around Lake Louise) overlies previous storm snow at upper elevations and rain-crusts below 1800 m. Recent strong winds have created wind-slabs in the alpine. Multiple buried crusts are present in the mid-pack on solar aspects. The basal snowpack remains weak with facets and depth hoar. A field team today on Mt. Whymper found large (10mm) depth hoar and a generally weak snowpack in the alpine.
Weather Summary
Friday: Light upslope winds and 2-4cm or more possible within convective cells. 1700-1900m freezing levels in the afternoon.
Saturday: A trough will begin to produce very light precipitation. Freezing levels 2000-2200m in the PM.
Terrain and Travel Advice
- Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
Avalanche Problems
Wind Slabs
Recent snow (15-40 cm in past week) are suspected to have formed wind slabs in the alpine. We don't have many observations of this but watch for them locally.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2
Deep Persistent Slabs
The weak basal facets and mid-pack facets/crusts remain a concern, and will remain so for the foreseeable future.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3