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Archived

Avalanche Forecast

Dec 12th, 2020–Dec 13th, 2020
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
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
1: Low
The avalanche danger rating at treeline will be low
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

Regions: Banff Yoho Kootenay.

Watch for power sloughing of the faceted surface snow in steep terrain. Although fairly small, they can travel far and fast. Great ski quality for December.

Weather Forecast

Mainly cloudy with continued colder temperatures (-18 to -20C in the AM) with a slight increase in wind which could gust moderate above 3000m. Some flurries possible but only trace amounts. Winds will increase on Monday and especially Tuesday.

Snowpack Summary

20-40 cm of faceted snow sits on the Dec 7th layer of sun crust, facets or surface hoar depending on your location. The Nov. 5th crust / facet layer persists at the bottom of the snowpack and continues to weaken over time. Snowpack depths are 90-160cm at tree line.

Avalanche Summary

There were numerous reports of loose, dry avalanches up to sz 2 in steeper alpine features like gullies which were running far on Saturday. The theory is the 20-40cm received last week has faceted and not been exposed to any wind. Even light winds today may have initiated these. Similar types of avalanches were observed in Little Yoho.

Confidence

Wind speed and direction is uncertain

Avalanche Problems

Loose Dry

20-40 cm of recent snow has faceted. In steep, alpine features, wind or people can start a small avalanche that will run far on the sun crust, facets or isolated surface hoar it lies on (Dec.7 layer).This trend may increase over the next few days.

  • Be careful of loose dry power sluffing in steep terrain.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2

Deep Persistent Slabs

The Nov 5 crust has facets above and below it, and exists up to 2500m on shady aspects and higher on solar aspects. We have only 1 observation of a deep slab avalanche since the storm, but it is still on our minds in shallow areas.

  • Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
  • Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 1 - 2.5