Archived

Avalanche Forecast

Nov 17th, 2011–Nov 18th, 2011

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.

Easily triggered avalanches up to size 1.5 have been observed in the last week. Open steep terrain with wind loading should be carefully evaluated or avoided. This severely limits choice as this is the terrain with enough snow to travel. JBW

Weather Forecast

Snowpack Summary

Avalanche Summary

Confidence

Due to the number and quality of field observations

Avalanche Problems

Persistent Slabs

Steep open slopes at and above treeline have a soft to hard wind slab that is sensitive to human triggering near the ground on the basal depth hoar. In isolated areas the Nov 7 surface hoar layer fails and then steps down. Sa size 1.5 at Bow Summit

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Wind Slabs

All slopes that look inviting for skiing have a wind slab over depth hoar layering. Cracking, whumphing and skier triggered avalanches have been observed. This layer collapses with Easy results. Pick lower angled low consequence terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2