Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
Watch for signs of wind slab formation and be cautious around thin areas where the deeper facets may still be triggered.
Confidence
Moderate
Avalanche Summary
Lake Louise triggered small wind slabs up to size 1.5 with explosives near ridge crests. A skier-triggered avalanche also occurred up Chickadee Valley on Saturday with no injuries.
Snowpack Summary
Since December 7, 5 to 10 cm of snow has fallen, and strong to extreme west winds on Friday have 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
Monday brings moderate NW winds in the alpine, no snow, and treeline temperatures in the -4 to -9C range.
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
Expected Size: 1 - 2
Deep Persistent Slabs
Weak facets exist at the base of the snowpack. Large open slopes at treeline and in the alpine remain suspect.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 3