Avalanche forecast

Northwest Inland

Dec 25 – 26, 2011Avalanche Canada
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Avalanche danger

Tue
Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Wind slabs continue to grow in lee and cross-loaded terrain in the alpine and at treeline.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Persistent slabs have now formed at all elevations where the mid December buried surface hoar/crust/facet layers exist. Reactivity has probably decreased somewhat, but the consequence of an avalanche remains high.

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

A series of frontal systems will affect the region over the next several days bringing periods of moderate to heavy precipitation and very strong winds. Monday: 10-15cm of snow. Very strong S-SW winds. Freezing level (FL) rising to around 1000m. Tuesday: 5-10cm. Moderate to strong SW winds. FL around 800m. Wednesday: 10-15cm. Strong SW winds. FL rising to 1500m.

Avalanche Summary

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

Snowpack Summary

Over the past week the Hankin/ Hudson Bay area received up to 40cms of new snow accompanied by strong southwest winds. Storm slabs and wind slabs have formed and may be susceptible to human triggering. There is now around 55-70cms of snow sitting on a surface hoar/crust/facet combo which is the result of the early December dry spell. This crust is widespread and exists in most start zones up to 2000m. Facets can reportedly be found above or below the crust. Prior to being buried, the surface hoar was destroyed by high winds in the alpine, but still coexists with the crust at treeline and below. What is the tipping point of this weak interface? In areas where this interface has reached its threshold, natural and human triggered avalanches up to size 2.5 have occurred. If they have yet to happen, I suspect they are gaining some strength but would still react to a rider trigger, especially in steeper, unsupported terrain features. In short, the upper snowpack is variable and deserves caution. It will also see increased load with forecast wind and snow. Beneath this the midpack is well settled and strong.

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