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Archived

Avalanche Forecast

Jan 19th, 2017–Jan 20th, 2017
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
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
3: Considerable
The avalanche danger rating at treeline will be considerable
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.

There is uncertainty around the deep persistent facets, how they will react to a user, and what will trigger them naturally. The best way to manage this uncertainty is through conservative terrain choices, and limiting exposure to overhead hazard. SH

Weather Forecast

A slow cooling trend over the next 3 days (-7 to -12C in the alpine) with dying SW winds.  No major snow is in the forecast. 

Snowpack Summary

10-30cm of new snow in the region(deeper amounts near the divide) with some wind slabs formed in lee terrain.  The upper snowpack consists of wind layers of various thicknesses.  The lower snowpack consists of facets and depth hoar, and below treeline the entire snowpack mainly consists of facets to ground.

Avalanche Summary

Many avalanches to size 2.5 have been reported in the last 24 hours. A size 1.5 skier accidental in the canyon on the approach to Bow Hut was reported yesterday with no involvement. A size 2 avalanche was reported from yesterday afternoon over the ice climb Cascade Falls, and explosive results at Lake Louise ski hill to size 2.5 to ground.

Confidence

Due to the number and quality of field observations on Thursday

Avalanche Problems

Deep Persistent Slabs

The midpack in most areas is weak and facetted. Any slab sitting overtop of this weakness should be considered suspect and there is a high level of uncertainty around this layer.
Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Wind Slabs

Recent winds  ranging from East to SW have created some new windslabs in alpine and treeline features. In some cases, these have been observed to provide enough weight to step down to the deep persistent layer, causing a larger avalanche.
If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2