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Archived

Avalanche Forecast

Jan 15th, 2021–Jan 16th, 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.

The January 11 surface hoar is buried by up to 40cm of recent snow and has proven to be sensitive to human triggering where it is found. Take the time to dig to look for this before committing.

Continued winds will keep hazard raised into the weekend.

Weather Forecast

Winds shift to the NW gusting 40 to 60km/h in the alpine into Saturday as a ridge forms over the region. Valley bottom temperatures will approach 0C Saturday as alpine temperatures rise from -15C over night. Winds shift back West late Saturday as the next system ,a bit to the North, brings the potential for a temperature inversion and light precip. 

Snowpack Summary

15-40 cm of recent snow has been redistributed in the alpine and open areas into treeline by mod to strong SW winds. The top 120cm in the snowpack displays 4 persistent layers. The Jan 11 surface hoar (6mm) is down 15-40cm and remains reactive where found. The Dec persistent layers are less reactive but produce sudden results when they fail.

Avalanche Summary

A widespread natural avalanche cycle occurred on Wednesday up to sz 3.0. Most were alpine windslabs or treeline storms slabs. Others of note: Cascade Falls sz 3.0, Pilsner Pillar, Twisted and Silk Tassel to sz 2.5, Whymper S and N several sz 2-3.0.

Explosive control at the ski hills Friday created small windslabs 10-20cm deep but limited to sz 1-1.5

Confidence

Due to the number of field observations

Avalanche Problems

Wind Slabs

The recent 15-40cm of snow has been redistributed by Mod to Strg SW winds forming wind slabs in the alpine and into open areas at treeline. Winds do not look to be diminishing, and a shift in direction could allow for further development.

  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
  • Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

Four persistent weak layers now exist in the top 120cm of the snowpack. The January 11 SH is down 15-40cm and is sensitive to triggering where it exists. The deeper layers are less reactive but continue to produced sudden results in tests.

  • Be wary of slopes that did not previously avalanche.
  • Use caution on convex rolls at tree line and below where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible

Expected Size: 1 - 2