Avalanche Forecast

Issued: Nov 28th, 2020 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

Find the best snow in wind sheltered areas. A lack of any decisive data on the basal crust is keeping it on our radar for now. 

Summary

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

Saturday night: Partly cloudy, light to moderate southwest wind, freezing level dropping to valley bottom.

Sunday: Sun and cloud, light to moderate southwest wind, freezing level 800-1000 m.

Monday: Up to 5 cm new snow, moderate southwest wind, freezing level 700 m.

Tuesday: Clear, light NW wind, freezing level 500 m.

Avalanche Summary

Explosive control work produced size 1-1.5 wind slab avalanches on Friday. We have received no reports of recent natural avalanche activity.

Our eyes and ears in the mountains are limited at this time of year and may continue this winter due to fewer professional observations. If you see anything while out in the field, please consider sharing it with us and fellow recreationists via the Mountain Information Network (MIN). Photos are especially helpful. A big thank you to those that have already shared their observations thus far.

Snowpack Summary

Previous southerly wind has formed wind slabs in lee terrain features at upper elevations. In more sheltered areas, 10-15 cm may overly a layer of weak and feathery surface hoar (observed at Kootenay Pass).

Treeline snowpack depths sit around 100 to 150 cm in the north and 50 to 100 cm in the south of the region. 

Melt-freeze crusts from mid- and early-November are generally found 30 cm below the snow surface and 30 cm up from the ground, respectively. Most reports indicate that the bonds at the interfaces with these crusts are improving.

Terrain and Travel

  • Be careful as you transition into wind affected terrain.
  • Be aware of the possibility for full depth avalanches due to deeply buried weak layers.
  • Be cautious of buried obstacles especially below treeline.

Problems

Wind Slabs

An icon showing Wind Slabs

Previous southerly wind has formed wind slabs in lee terrain features at upper elevations.

Aspects: North, North East, East, North West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

A crust exists near the base of the snowpack. A lack of any decisive data on this layer is keeping it on our radar for now. The few reports we have indicate an improving bond to the overlying snow in most areas. But potential for full depth avalanches may exist in areas where weak, sugary facets overly this crust, especially in areas of smooth ground cover such as scree slopes, grassy slopes, or rock slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

1.5 - 2.5

Valid until: Nov 29th, 2020 4:00PM