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Archived

Avalanche Forecast

Nov 18th, 2021–Nov 19th, 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
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

The natural cycle has tapered off, but explosive work today triggered numerous avalanches to size 2.5.

Weather Forecast

For Friday expect a mix of sun and cloud, with no precipitation, light winds, and highs around -8C.  For the weekend, the forecast is for light precipitation 5-10 cm with gusty SW winds and highs around -10C.

Snowpack Summary

Several cm of fresh snow exist over a surface crust (below 2100m). Recent storm snow (5 day total of 65-90 cm) is settling. Wind slabs exist in alpine and down into tree-line elevations. A melt/freeze crust and/or facets exist near the ground (in some locations).  Snowpack depths at tree-line average 60-110 cm

Avalanche Summary

Explosive work around Lake Louise, Sunshine, and on Mt Bosworth produced numerous avalanches today to size 2,5.  Most avalanches were windslabs 20-40 cm thick and some failed on the basal facets. It remains likely a person could trigger  or remote trigger an avalanche on steeper slopes that have not yet slid.

Confidence

Due to the number and quality of field observations

Avalanche Problems

Wind Slabs

Reactive windslabs exist in the alpine and down into some tree-line locations.  Explosive work triggered numerous avalanches to size 2 on Thursday generally 20-40 cm thick.

  • Watch for surface cracking and stiffer surface layers of snow. Avoid wind loaded terrain.
  • Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Deep Persistent Slabs

A facet or facet crust layer exists at the bottom of the snowpack. Today and over the past week several avalanches had long propagations and ran far on this layer up to size 3. Be suspicious or steer clear of steeper terrain that has not slid.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1.5 - 2.5