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Archived

Avalanche Forecast

Dec 31st, 2021–Jan 1st, 2022
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
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
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Banff Yoho Kootenay.

Winds, warming, and a bit of snow expected to arrive this weekend will be a significant change that could really shake up the snowpack. Make conservative terrain selections and consider your exposure to overhead terrain. Natural activity is expected.

Weather Forecast

A low pressure system will cross the divide Saturday. As temperatures rise 10 to 15 degrees C, expect alpine winds to reach extreme values by the afternoon as light snowfall starts on the divide. Snow continues at a moderate rate for Sunday as the winds diminish to strong midday and temperatures rise a further 10 degrees C. 

Snowpack Summary

10-40 cm of snow last week and recent wind from various directions has developed wind slabs in the alpine. There is 50-70 cm over the Dec. 2 crust/facet combo which exists below 2200m and appears to be waking up as a persistent weak layer. Shallow areas (<100 cm) have weaker basal facets which also present cause for concern as temperatures rise.

Avalanche Summary

There was a skier triggered size 2 avalanche at 2000m in Kootenay NP Thursday. This appears to have been on the Dec. 2nd crust/facets. It also appears that another party triggered a smaller slab in the same area today. The ski hills worked with recent windslabs in the alpine yesterday however nothing new was reported today.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Avalanche Problems

Wind Slabs

Last week's snow and winds from a variety of directions have created wind slabs in the alpine. As winds increase through Saturday we expect natural activity in the alpine and slab development at treeline.

  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Minimize overhead exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

The Dec. 2 crust/facet layer down 50-70cm has not presented as a widespread problem, but a skier triggered avalanche in Kootenay Thursday shows it has started to wake up. We are concerned with the potential for further slab development this weekend.

  • Be cautious with steep or unsupported slopes.
  • Be very cautious if you notice slab development at treeline and below..

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Loose Dry

A long period of cold has lead to faceting of the upper snowpack. This weak snow will be more sensitive to triggering and will also allow avalanches to run further and faster. We expect the wind to generate a significant amount of loose dry activity.

  • Loose dry avalanches could easily trigger Wind Slab or Persistent Slab avalanches.
  • Be careful of loose dry sluffing in steep, confined or exposed terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 1.5