Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
Fresh wind slabs can be found in the alpine and in some locations at treeline.
Ice climbers: avalanches may run further than expected given the dry, sugary snow in avalanche paths.
Confidence
No Rating
Avalanche Summary
MIN and ski hill observations Friday described ski and explosive triggering of a few small, thin wind slabs and wind-driven sluffing out of extreme terrain although visibility was limited. A few further reports of small windslabs from the ski hills Saturday.
Snowpack Summary
5 to 10 cm of snow since Dec 7 and strong to extreme west winds Friday has created slabs in the alpine and some treeline features. The recent snow sits on a layer of facets and surface hoar that persists in isolated locations.
The middle and bottom of the snowpack are weak, with depth hoar and facets near the ground.
An average of 60-100cm of snow can be found at treeline elevations.
Weather Summary
Alpine winds shifted to the NW and became light to moderate Saturday. As a weak ridge forms Sunday, these winds will persist, skies will clear and temperatures will drop a few degrees to range between -8C and -12C near treeline.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.
Avalanche Problems
Wind Slabs
Extreme W to SW winds overnight Thursday and a few cm new snow have developed slabs in lee alpine and treeline terrain. These will be bigger in areas with more new snow and may run further than expected if they pick up facetted snow in steep gullied terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Deep Persistent Slabs
Weak facets exist at the base of the snowpack. The new snow and wind over the last few days may have made this weak layer more reactive. Large open slopes at treeline and in the alpine remain suspect.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 3