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Archived

Avalanche Forecast

Dec 8th, 2023–Dec 9th, 2023
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.

Up to 60+ cm of recent storm snow will take time to settle over the weaker basal layers. A spike in wind starting Saturday afternoon will be a factor in keeping the danger elevated.

Confidence

Moderate

Avalanche Summary

Avalanche control Friday produced results to size 2.5. Most were observed initiating on the basal facets, but it is unknown what layers many slid on. As skies clear, there are more observations of natural avalanches from the last few days. Most are up to size 2.5, failing on or near the ground.

Snowpack Summary

Up to 60 cm of storm snow overlies the Dec 2 layer of surface hoar, facets and a crust. Below this layer are basal facets and a crust formed in late October. We suspect there is some separation between these weak layers in the alpine, but at treeline and below, they are essentially the same layer. Snow depths range from 80-100 cm at treeline and up to 140cm observed in alpine locations.

Weather Summary

Winds will increase mid-day Saturday in the alpine to strong, starting NW and switching to SW. Temperatures will cool to -14 to -16 with mainly sunny skies. A trace of snow on Sunday with continued strong winds.

For more information, click Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.

Avalanche Problems

Wind Slabs

Winds will start to increase mid-day at higher elevations. With lots of snow to transport, wind slabs could form and fail quickly. Once initiated, they could trigger deeper slabs. Watch closely for their development and consider your exposure to overhead terrain in gullies.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

Deep Persistent Slabs

The lower snowpack comprises two layers. Facets and a crust lie at the base, and the Dec 2nd layer of surface hoar, facets and crust above. These layers may be separated a bit in the alpine but, in many places, are right above each other. Avalanches can be significant in size and run below treeline.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3