Avalanche Forecast

Issued: Nov 19th, 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, Wind Slabs and Wind Slabs.

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Another cold day ahead, followed by a warming trend and little to no snow in the immediate forecast.

Summary

Weather Forecast

Snowpack Summary

Avalanche Summary

Confidence

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. Wind loading triggered Na avalanches up to size 2.5 that failed to ground in the last 48 hrs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Wind Slabs

All slopes that look inviting for skiing have a wind slab over depth hoar layering. Cracking, whumphing, natural 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

Likely

Expected Size

1 - 3

Wind Slabs

Several, 2 day old, downed avalanches observed on the Hwy 93 N failed in the midpack (photos on the ACMG mountain conditions report), beneath cliffs or on convex rolls. We are uncertain of the failing layer, but it could be preserved surface hoar.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Nov 20th, 2011 4:00PM