Avalanche forecast

Northwest Coastal

Dec 11 – 12, 2012Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Wind slabs are likely to be found on alpine slopes and behind ridges and ribs at treeline. Storm slabs may be lurking in areas not affected by the wind.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–7
    A deeply buried facet/crust weakness exists. While the likelihood of triggering it is low, the consequences could be a very large and destructive avalanche.

Avalanche Summary

Large natural avalanches were heard across the valley from Shames on Tuesday. On Monday, explosives triggered several size 1.5-2.5 slabs on wind-loaded slopes north of Stewart, one of which ran on facets at the ground.

Confidence

Fair - Due to limited field observations

Weather Forecast

Wednesday: Moderate W winds. Alpine temp -7. Light snow. Thursday: Strong W winds. Alpine temp -7. Moderate snow (locally heavy).Friday: Light S winds. Alpine temp -7. Moderate to heavy snow.

Snowpack Summary

Warm temperatures on Tuesday led to upside-down storm snow (dense snow over lighter snow) and rain at low elevations. Recent storm snow has been redistributed by very strong winds, creating wind slabs which may now be buried on a variety of slopes.  The mid-pack is generally well-settled. A November facet/crust layer can be found near the base of the snowpack. Sporadic releases are still occurring on this layer with a heavy trigger. Above about 1000 m, the snowpack is 150-250 cm deep. Below about 1000 m, snowpack depths peter out pretty quickly.

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