Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
The recent new snow and strong winds have resulted in an elevated avalanche danger that remains in the forecast region.
Confidence
Moderate
Avalanche Summary
The ski hills continue to report triggering of wind slabs with ski cuts and explosives, ranging up to size 2, and 10 to 40 cm deep.
There is visible evidence of a widespread avalanche cycle that occurred during the storm, particularly in the western parts of the region. We have observed failures at both the wind slab interface and the deep persistent problem.
Snowpack Summary
Up to 20 cm of storm snow fell last week. This new snow, combined with strong winds, has formed wind slabs throughout the alpine and treeline. The mid and lower pack is faceted and weak east of the divide, and more settled in western regions. A weak interface exist near the ground on the deep persistent layer (Nov 9 and Oct 20 interfaces). Snowpack depths at tree-line is about 60 cm in eastern areas and 100 cm west of the divide.
Weather Summary
A series of weak systems will move through the forecast region over the weekend. Light precipitation could result in 2 to 5 cm of snow accumulation by Monday. Winds at higher elevations will remain elevated, and temperatures at valley bottoms will hover around 0°C.
Terrain and Travel Advice
- Avoid freshly wind-loaded features, especially near ridge crests, rollovers, and in steep terrain.
- Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.
Avalanche Problems
Wind Slabs
Strong southwest winds have created slabs in lee features at treeline and in the alpine. While these slabs can be expected to fail on the new snow interface, they may also step down into the mid-pack facets resulting in larger avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Deep Persistent Slabs
Weak facets and depth hoar associated with crusts near the base of the snowpack continue to produce slab avalanches 60 -100 cm deep. Any area with a stiffer slab over the mid-pack facets has the potential to generate an avalanche that steps down to these layers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1.5 - 3