Avalanche forecast

Banff Yoho Kootenay

Nov 20 – 21, 2011Parks Canada
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Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

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

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    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.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    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.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    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.

Weather Forecast

Snowpack Summary

Avalanche Summary

Confidence

Regions covered