Avalanche forecast

South Coast

Dec 29 – 30, 2011Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–6
    Wind slabs have developed in exposed lee and cross-loaded terrain and may be quite reactive, especially where they over-ride last weekend's rain crust or weak facets (sugar snow) from the early December dry spell.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Weaknesses exist within or at the base of the new storm snow. Natural avalanches will become more likely with each successive storm.

Confidence

Fair - Intensity of incoming weather is uncertain on Friday

Weather Forecast

Thursday night: 10-15cm snow. Freezing level 900m.Friday: 5-10cm snow. Freezing level rising briefly to around 1300m near the coast, then falling back to 900m. Strong westerly winds.Saturday: A cool sunny day. Sunday: Dry but mild, with cloudy periods possible.

Avalanche Summary

Highways avalanche control triggered size 3 slabs up to 1m deep. A skier was carried some distance by an avalanche in the Duffey Lake area on Thursday afternoon. I expect avalanche activity to continue, with less naturally-triggered and more human-triggered events occurring over the next couple of days.

Snowpack Summary

Up to 50cm of recent snow has been shifted by southerly winds into wind slabs on lee slopes in the alpine and at treeline.Below the recent storm snow, three weaknesses exist in the upper snowpack. A surface hoar layer formed in early December overlies facets and is down about 60cm. It is giving easy-very easy, sudden collapse results in snowpack tests.A second surface hoar layer buried around Christmas is also giving easy, sudden planar results.A crust which exists to around treeline, buried on December 17th, adds to the complexity of the snowpack.Persistent weaknesses seem to be more of a concern around the Duffey Lake area than in the Cascades (Coquihalla and Allison Pass).The mid and lower snowpack are generally well-settled and strong.

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