Avalanche Forecast
Issued: Dec 23rd, 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
A buried weak layer has produced recent avalanche activity. The best approach is to select conservative terrain at this time.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations.
Weather Forecast
WEDNESDAY NIGHT: Mostly clear skies, light southwest wind, alpine temperature near -12 C.Â
THURSDAY: Mainly sunny, light southerly wind, alpine temperature near -4 C with a chance of a weak temperature inversion.
FRIDAY: Mix of sun and cloud, light to moderate south wind, alpine temperature near -5 C.Â
SATURDAY: Mainly cloudy with scattered flurries, light west wind, alpine temperature near -7 C.
Avalanche Summary
On Monday there was a report of a human triggered avalanche that was suspected to have run on buried surface hoar. The MIN report can be view here.
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 last week 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. The distribution of this layer is variable. In some areas it's surface hoar and in others it may be surface hoar on top of a crust and in others it is very hard to find if it exists at all. 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, a crust that was buried in early November can be found. 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 24th, 2020 4:00PM
