Avalanche forecast

Sea To Sky

Dec 8 – 9, 2011Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–3
    Weak wind slabs may still be lurking below ridge crests, behind terrain features, and in cross-loaded gullies.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–7
    The right trigger (big air onto steep unsupported slope, sled track trenching deep in a thin area) could have disastrous consequences. The greatest concern is in the Whistler area on slopes with variable snowpack depths above 1900m.

Confidence

Fair - Due to limited field observationsfor the entire period

Weather Forecast

Friday: Mostly sunny and dry with light winds. The strong temperature inversion continues with above freezing alpine temperatures and the possibility of valley cloud. Saturday: Increasing clouds and light southwest winds with light precipitation starting in the evening. The temperature inversion is expected to dissipate with freezing levels as high as 1400m. Sunday: Light snowfall, freezing levels lowering to 900m, and light to moderate southwest winds.

Avalanche Summary

There have been no recent avalanches reported. Although the likelihood of triggering deep persistent slab avalanches is low, the potential consequences are still very high.

Snowpack Summary

Basal depth hoar with an associated crust is prevalent in thin snowpack areas, and especially problematic where it is overlying summer firn. Above that, and down 1-2m, are two more crusts mixed with facets, depth hoar, and surface hoar. The overlying snow has recently settled and stiffened and the facets have started to round and strengthen, but recent compression tests in a shallow snowpack area produced moderate sudden collapse results on this deep persistent weakness. The snow surface is wind hammered in wind-exposed areas, crusty on sun-exposed slopes, and faceted powder with large surface hoar on shady sheltered slopes. A thick rain crust is down 20-40cm and extends up to treeline elevations.

Regions covered