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Archived

Avalanche Forecast

Dec 7th, 2021–Dec 8th, 2021
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Banff Yoho Kootenay.

High winds are forecast for Wednesday morning. Watch for fresh wind slabs in the alpine.

Weather Forecast

Strong SW winds in the alpine are forecasted throughout the region for Wednesday morning. Up to 10 cm of snow is expected by the end of the day. Temperatures will remain cool.

Snowpack Summary

In the alpine conditions range from scoured, to wind effected to pockets of fresh wind slabs. The Dec 2 rain crust has formed up to 2200 m and is now covered by 5-30 cm of fresh snow depending on elevation. The lingering Nov 15 interface is down 50-100+ cm and the Nov 5 crust/facet layer is found near the ground. 90-200 cm of snow at treeline.

Avalanche Summary

No new natural avalanches observed on Tuesday. The Ski Hills reported several small explosive triggered avalanches. One significant skier accidental size 3  was triggered on Lipalian Mtn (near Lake Louise) on Sunday. This was a steeper slope in a cross-loaded, thinner snowpack area which is typical of the type of terrain to be more concerned about.

Confidence

Wind speed and direction is uncertain on Wednesday

Avalanche Problems

Deep Persistent Slabs

We continue to see occasional high consequence avalanches on the Nov 5 crust/basal facets in specific terrain features. Some slabs have initiated on this layer, while others were "step down" avalanches triggered as wind slabs or cornices hit them.

  • Avoid steep convexities or areas with a thin or variable snowpack.
  • Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Wind Slabs

Strong winds on Wednesday and some new snow will increase the wind slab hazard in the alpine and exposed treeline locations.

  • If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2