Avalanche Forecast

Issued: Nov 17th, 2011 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs and Wind Slabs.

Brad White, Parks Canada

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

Summary

Weather Forecast

Snowpack Summary

Avalanche Summary

Confidence

Due to the number and quality of field observations

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

Valid until: Nov 18th, 2011 4:00PM