Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Recent wind, snow, and mild temperatures led to an avalanche cycle on Wednesday.
As forecasts call for continued moderate west winds, further slab development is likely into Saturday.
The potential for natural avalanche activity remains.
Confidence
Moderate
Avalanche Summary
Wednesday's wind event following the latest storm led to a limited avalanche cycle.
Although visibility remained poor today, given the debris that is visible in the Field area, we would suspect slabs up to sz 2.5 originated in the alpine and scrubbed to the ground in the tracks.
The ski hills report triggering many wind slabs with ski cuts and explosives up to sz 2, 10 to 40cm deep. Each hill also triggered a sz 2 plus slab on the deep persistent layer with explosives.
Weather Summary
Southwest winds are forecast to remain in the moderate to strong range but shift west Friday. Treeline temperatures near -4C and scattered flurries will produce trace amounts of snow.
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 on Wednesday combined with up to 20cm of storm snow 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: Very Likely
Expected Size: 1 - 2.5
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
Loose Dry
While winds have died down from their peak values, the potential for wind-generated loose snow avalanches should remain on the radar for climbers in gullied terrain as winds remain elevated into the weekend. The main concern here is that these small events trigger a slab.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 1.5