Avalanche Forecast
Issued: Dec 6th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
We have very limited information on current conditions in the region. If you find your way into the mountains, please share your observations on the Mountain Information Network!
Summary
Confidence
Weather Forecast
Monday night: Cloudy. Moderate southwest wind. Treeline high temperatures around -8.
Tuesday: Cloudy with flurries starting in the late afternoon. Strong southwest wind. Treeline high temperatures around -3. Freezing level 800 m in the north, 1300 m in the south.
Wednesday: New snow 10-20 cm. Strong southwest wind. Treeline high temperatures around -8.
Thursday: Flurries up to 5 cm. Light to moderate westerly wind. Treeline high temperatures around -12.
Avalanche Summary
Over the weekend, some loose dry sluffing and thin soft slab reactivity were seen in steep terrain and near ridge crests in the neighboring Sea to Sky region. The most recent reports we have from the inland are of explosives producing a size 2 wind slab avalanche in the Hurley last Thursday.
Snowpack Summary
Recent weather patterns have resulted in varied conditions between the north and south of the region.
The south, having endured warmer temperatures and more rainfall, is largely below threshold for avalanches at most elevations. Surface snow has seen extensive wind effect, scouring the crust clean in some areas, while piling up to 40 cm over it in others.
In the north, a skiff of snow may be sitting over a layer of surface hoar crystals, older wind affected snow in the alpine, a thick crust below 1800 m or a combination of these.
A couple of buried weak layers produced large avalanches during a previous storm. Snowpack models and observations in the neighboring Sea to Sky region indicate that these layers have been reset by previous rain at treeline, but uncertainty remains around their status in the alpine. These include a layer of surface hoar down an estimated 90-120 cm and deeper crust/facet combo layer.
Average snowpack depths in the alpine are now likely closer to 150-200 cm. Below treeline, depths of 30-50 cm have been reported around 500 m, decreasing dramatically with elevation, and still below threshold for avalanches in many areas.
Terrain and Travel
- Make observations and assess conditions continually as you travel.
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Even a small avalanche can be harmful if it pushes you into an obstacle or a terrain trap.
Problems
Wind Slabs
Anywhere soft surface snow remains available for transport, we expect wind slab development as winds pick up late Tuesday. Although thin, they may be surprisingly reactive where they sit on a weak layer of surface hoar or a slippery crust.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
This problem may exist in the north of the region. We have few observations and plenty of uncertainty around whether a buried weak layer remains a problem at upper elevations. Very large avalanches are suspected to have run on this layer during the atmospheric river.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 7th, 2021 4:00PM
