Avalanche Forecast

Issued: Dec 24th, 2020 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada MBender, Avalanche Canada

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 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

THURSDAY NIGHT: Clear periods, light southwest wind, alpine temperature near -6 C with possible temperature inversion.

FRIDAY: Mix of sun and cloud, light southwest wind, alpine temperature near -4 C with possible temperature inversion.

SATURDAY: Scattered flurries, accumulation 3-5 cm. light southwest wind, alpine temperature near -8 C.

SUNDAY: Mainly cloudy with sunny breaks, light west wind, alpine temperature near -10 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 last weekend throughout the region. The MIN posts tell the story. You can view them all here

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. Winds blowing from a variety of directions 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. 

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

An icon showing Wind Slabs

Recent new snow combined with moderate winds have created wind slabs in the lee of terrain features on a variety of aspects.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Persistent Slabs

An icon showing Persistent Slabs

This layer was touchy through last weekend producing large avalanches. The slab rests on a persistent weak layer which has the capacity to propagate avalanches across terrain features.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Dec 25th, 2020 4:00PM