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Archived

Avalanche Forecast

Jan 14th, 2021–Jan 15th, 2021
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
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.

The Jan 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. Have a dig and look for this layer.

Strong winds forecasted for Friday will keep the hazard elevated.

Weather Forecast

Friday will be mainly cloudy with isolated flurries, accumulating up to 2cm of snow. Ridge top winds are forecasted to increase early Friday morning (30-80km/hr from the West) and gradual decrease by the evening. A temperature inversion is also forecasted to move in Thursday evening, expect alpine temps around -5 Friday morning.

Snowpack Summary

15-40 cm of recent snow with the incoming strong SW winds will form wind slabs in exposed locations. The top 120cm in the snowpack boasts 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. The Bow Lake area boasted dozens of avalanches up to sz 2.0. Other notables included Cascade Falls sz 3.0, Pilsner Pillar, Twisted and Silk Tassel up to sz 2.5, Whymper S and N several sz 2-3.0.

Explosive control on Wednesday also produced results up to sz 2.5 on Mt. Bosworth.

Confidence

Avalanche Problems

Wind Slabs

The recent 15-40cm of new snow and strong SW winds will be forming wind slab in exposed areas and have the potential to step down to deeper layers in the snowpack.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Persistent Slabs

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

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

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3