Avalanche Forecast
Issued: Dec 19th, 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.
zryan,
Avalanche Canada
Avoid wind loaded areas where human triggering remains a concern. If winds pick up today, there is a lot of snow available for transport to create fresh, reactive slabs.
A buried persistent weak layer continues to warrant careful terrain selection and diligent decision making.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
Sunday Overnight: Light northerly winds and partially cloudy skies. Temperatures dropping to -15 C in the alpine.Â
Monday: Partially cloudy with a chance of light flurries. Alpine temperatures around -12 C. Light to moderate westerly winds at ridgetop.
Tuesday: Overnight temperatures dropping to around -15 C. A mix of sun and cloud with moderate to strong southwest winds at ridgetop. Temperatures rising with an alpine high of -8 C. Cloud cover increasing into the evening.
Wednesday: Mainly cloudy and snowing, 5-20 cm accumulation possible. Moderate to strong southwest winds at ridgetop. Alpine temperatures rising to around -4 C by the afternoon.
Avalanche Summary
On Sunday, operators reported a natural avalanche cycle from overnight, with avalanches up to size 3 running almost full path. Explosive control work produced size 1-2.5 storm slabs in the alpine and treeline.Â
On Sunday, one notable ski cutting result produced a size 1.5 persistent slab avalanche at treeline on the early December crust.
On Saturday, operators reported numerous size 1-2 loose dry and storm slab avalanches.
Snowpack Summary
An intense storm came through the region on Saturday, bringing 40-70 cm of new snow. This new snow has started to settle out, with cold temperatures decreasing slab properties. In wind loaded areas, wind slabs continue to be a concern and remain reactive to human triggering.Â
Below this new snow, 50-100 cm of more consolidated snow sits over a substantial crust that formed in early December. This crust is up to 20 cm thick and is present across aspects below 2400m. A layer of weak facets (sugary snow) can found above this crust. This problem is particularly hard to predict and tricky to manage. For this reason wide, conservative terrain margins and disciplined backcountry travel techniques will be very important. Get more details and photos in our forecaster blog.Â
The lower snowpack consists of a variety of early season crusts and mainly moist snow. Snowpack depths range from 100-200 cm at treeline elevations and taper quickly below 1800 m.
Terrain and Travel
- Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
- Be careful as you transition into wind affected terrain.
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
Problems
Wind Slabs
Saturday's intense storm brought 50-70 cm of new snow. In wind loaded areas, human triggering will still remain a concern. If the wind picks up today, there is a lot of snow available for transport and it will form fresh, reactive wind slabs.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A layer of weak facets (sugary snow) can be found down 100-150 cm over a crust that formed in early December. There has been a significant amount of new load on top of this layer. As we assess the influence of the new snow, it will be crucial to practice good travel habits and diligent decision making.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 20th, 2021 4:00PM
