Avalanche Forecast
Issued: Dec 22nd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
MBender,
Avalanche Canada
40 to 60 cm of snow now rests on a buried weak layer which has recently resulted in large avalanches. Take a look at this example. It's good time to adopt a conservative approach to selecting terrain.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations.
Weather Forecast
TUESDAY NIGHT: Broken cloud cover, moderate northwest wind, alpine temperature near -12 C.
WEDNESDAY: Scattered cloud cover, light to moderate west wind, alpine temperature near -3 C with potential for a light alpine temperature inversion.
THURSDAY: Mainly sunny, light southerly wind, alpine temperature near -2 C with potential for a light alpine temperature inversion.
FRIDAY: Mix of sun and cloud, light southwest wind, alpine temperature near -5 C.
Avalanche Summary
There was a smattering of reported natural and human triggered avalanches on Saturday throughout the region with humbling photos of large avalanches. The MIN posts from the weekend really tell the story, you can view them all here. This observation from Sunday on a north facing slope looks to be failing on the mid December surface hoar.
Snowpack Summary
A steady stream of storms over the past week has resulted in 30 to 65 cm of light density new snow across the region with areas to the east around Blue River getting the larger amounts. Southwest winds have built slabs in lee features at upper elevations.
An active weak layer is now down 40 to 70 cm below the surface. In some areas it's surface hoar and in others it may be surface hoar on top of a crust. The bond at this interface is poor and avalanches have recently failed on this interface in the east the region.Â
Near the base of the snowpack is a crust that was buried in early November. This crust likely has weak facets associated with it. There have been no recent avalanches reported on this layer, though it may be possible to trigger from shallow, rocky terrain.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
- Use careful route-finding and stick to moderate slope angles with low consequences.
Problems
Wind Slabs
Recent new snow combined with moderate to strong northerly wind have created wind slabs in the lee of terrain features.
Aspects: North East, East, South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
This layer was touchy through the weekend producing large to very large avalanches. The slab rests on a persistent weak layer which has the capacity to propagate avalanches across terrain features. Wind exposed features are expected to be particularly problematic.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 23rd, 2020 4:00PM
