Avalanche forecast

Sea To Sky

Dec 23 – 24, 2011Avalanche Canada
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Archived · expired 15 years ago

Avalanche danger

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

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Fresh windslabs exist below ridge crests, behind lee terrain features and in cross-loaded gullies. Windslab size and reactivity will increase with forecast weather.

Confidence

Fair - Intensity of incoming weather is uncertainfor the entire period

Weather Forecast

Saturday: 5cm of snow - strong southwest winds - freezing level at 1200mSunday: 20cm of snow - moderate southerly winds - freezinglevel at 800mMonday: 10-20cm of snow - moderate southwest winds - freezing level at surface

Avalanche Summary

Recent observations are limited to isolated human-triggered Size 1 fresh wind slabs. One was 20m wide by 20cm deep on a NE facing alpine slope.

Snowpack Summary

Alpine areas are wind-hammered with scoured and pressed surfaces, exposed crusts, and pockets of hard and soft wind slabs. Buried surface hoar and/or facets may persist 10-20cm below a weak rain crust on sheltered treeline slopes and below. Recent compression tests on a treeline slope produced easy to moderate sudden collapse results down 65cm on on this weakness where it was wind-loaded. Watch this layer as it gets more load and a thick cohesive slab develops, particularly below treeline where the buried surface hoar would be especially large. A strong mid pack overlies weak basal facets and depth hoar in shallow alpine areas. This deep persistent weakness may also deserve attention with more load.

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