Avalanche forecast

Northwest Inland

Dec 21 – 22, 2011Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Wind slabs have developed on lee and cross-loaded terrain in the alpine and at treeline. Rider triggered wind slabs are likely.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Reactive storm slabs have now formed at all elevations. Especially where the mid-December buried surface hoar/crust/facet layers exist.

Confidence

Fair - Track of incoming weather is uncertain

Weather Forecast

Thursday: Strong ridgetop winds from the SW with snow amounts near 10cms. Treeline temperatures near -5. Friday-Saturday: Freezing levels may rise to 1100m. Mix of snow and rain at lower elevations. Snow amounts near 12cms. Ridgetop winds strong from the west.

Avalanche Summary

No new avalanche activity has been reported. Any information (professional or recreational) from the field is highly appreciated. Please send your observations to [email protected].

Snowpack Summary

Early in the week the region received up to 20cms of new snow accompanied by strong southwest winds. Storm snow and wind slabs are forming. There could be up to 50cms total from last week's snowfall and the current snowfall loading the weak layers in the upper part of the snowpack. These weak layers are the December 12th surface hoar/crust/facet combo. What is the tipping point of this weak interface? In areas where this interface has reached its threshold avalanches have occurred. If they have yet to happen naturally, I suspect they are very touchy and will react to a rider trigger. Observations suggest there is faceting above and below the crust. The crust being a result from rising freezing levels, then the early December dry spell. This crust is widespread and is lingering in most start zones up to 2000m. In short, the upper snowpack is variable and showing easy shears in test results. The midpack seems to be well settled and strong.

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