Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Consistently strong winds have been the theme in the alpine and at treeline. Be especially warry of wind loaded slopes where ever encountered, as they likely hold touchy windslabs. As day are short, get out early and get home early.
Confidence
Moderate
Avalanche Summary
A large natural avalanche was observed yesterday in the alpine on Mount Fairview. Additionally, there have been natural, human and explosive triggered avalanches at Lake Louise and Sunshine ski hill's up to size 2 within 24- 48h. The wind slab has been the primary avalanche problem, however there are still avalanches stepping down to the deep persistent problem.
Snowpack Summary
Wind slabs have continued to build with very strong winds and recent snow. In isolated areas at treeline these slabs could be sitting on surface hoar. The early December storm has settled into a 20-40 cm layer at treeline. A rain crust up to 7cm thick exists within this storm snow as high as 2300 and is more prevalent in the south part of the region. This all overlies the deep persistent weak layers, consisting of surface hoar and basal facets. Treeline depths range from 50-90cm.
Weather Summary
Mostly cloudy skies and no new snow are forecast for Sunday. Winds are expected to decrease in intensity through Saturday night and shift to a northerly flow. Through the day on Sunday, winds should increase and shift back to a westerly flow by evening.
The alpine high is forecast at -6C and freezing levels will reach valley bottom.
For more information, click Mountain Weather Forecast.
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.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Avalanche Problems
Wind Slabs
Variable winds remain moderate to strong and are creating fresh windslabs in alpine and exposed treeline terrain. These slabs will likely be sensitive to human traffic in steep terrain and in isolated areas at treeline/below the windslab may overlay surface hoar.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Deep Persistent Slabs
The bottom 1/4 to 1/2 of the snowpack is weak and consists of layers of surface hoar, facets, depth hoar, and occasionally, a crust . If initiated, larger avalanches can result which hold the potential to run further than expected and reach below treeline elevations.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1.5 - 2.5