Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
We have entered a period of change in the snowpack. Increased winds, warmer temps, and new snow will add load to a very weak faceted snowpack. Expect to see an increase in avalanche activity over the weekend.
Confidence
Moderate
Avalanche Summary
The Banff field team was ski-cutting newly formed wind slabs Friday. These slabs were generally 10-15cm thick and propagating up to 40m at treeline. We suspect these new slabs to be more widespread and deeper in the alpine.
Snowpack Summary
Overall, the snowpack is shallow and weak with a base of facets and depth hoar. New snow and wind have begun to create slabs of varying thickness overtop of the weak faceted snowpack. We expect these to continue to build incrementally over the weekend as the storm moves in.
Total snowpack depths at treeline range from 60-120 cms.
Weather Summary
As another weather system pushes into BC, the Westerly flow will bring a much-needed reprieve from the cold temps. Saturday we will see increased cloud cover through the day with snow accumulation beginning in the evening. Forecasted snow values range from 5 -15cm by Sunday morning. Strong to Extreme winds Saturday will likely develop new slabs on exposed features at all elevations.
Terrain and Travel Advice
- Watch for fresh storm slabs building throughout the day.
- Uncertainty is best managed through conservative terrain choices at this time.
Avalanche Problems
Wind Slabs
Strong winds continue to build fresh wind slabs in alpine and treeline terrain. These new wind slabs overly a very weak faceted snowpack. If triggered the slab will likely gouge down to the deep persistent problem.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Deep Persistent Slabs
The whole snowpack is thin, weak and facetted, but the biggest facets and depth hoar are at the bottom. New snow, wind, and warm temperatures will gradually build a slab over top of this weak layer, and at some point over the next few days, we are expecting a small avalanche cycle failing on this layer. As this slab develops we could start seeing more avalanche activity below treeline on this problem.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5