Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
New wind slab development will keep the avalanche danger elevated at upper elevations.
Ice climbers: gully avalanches may run further than expected given the dry, sugary snow in all the avalanche paths.
Confidence
Moderate
Avalanche Summary
Minimal new avalanche observations in the region. Local ski hills were reporting small reactive winds slabs specific to immediate lee features at alpine and tree line elevations.
Snowpack Summary
A few cm of new snow and a lot of wind has created windslabs in the alpine and at treeline. These sit on a layer of facets and surface hoar that is likely to become a bad sliding surface in the future. 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
Northerly flow over the weekend will bring moderate to strong north winds (reverse loading) to the region. Cloud cover will persist through Saturday, with a clearing trend starting Sunday. Only a trace of snow accumulation is expected. Alpine temperatures will hover around -10°C, while valley bottoms will remain below freezing.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
- Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.
- Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.
Avalanche Problems
Wind Slabs
Extreme winds overnight Thursday and a few cm new snow have developed windslabs 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. New snow and wind over the next couple days may make this layer more reacive. Fresh windslabs may step down to the weak snow on the ground and result in larger, more destructive avalanches. Large open slopes at the treeline and in the alpine remain suspect.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5