Avalanche forecast

Kootenay Boundary

Dec 20 – 21, 2011Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    Fresh wind slabs are lurking below ridge crests, behind terrain features, and in cross-loaded gullies.

Confidence

Good - -1

Weather Forecast

Wednesday: Mostly clear with freezing levels in valley bottoms and moderate northwesterly winds. Thursday: Increasing clouds and freezing levels as high as 1300m, with moderate southwesterly winds. Friday: Light snowfall with freezing levels as high as 1300m, and moderate westerly winds.

Avalanche Summary

Recent reports include isolated human triggered Size 1 thin soft wind slab avalanches running on large surface hoar, on south through east facing treeline slopes.

Snowpack Summary

10-15 cm low density snow sits above a weak layer of large surface hoar and/or facets, with and associated crust on sun-exposed slopes. A sufficiently cohesive slab for fracture propagation and avalanche release has formed on wind-loaded slopes, but for the most part, the slab is neither deep nor stiff enough for large avalanches. We typically see dangerous slab avalanches start to occur when the depth to the weak layer reaches approximately 40cm. Check out the Forecaster's Blog link below for a discussion on incremental loading of potentially persistent weak layers. The mid and lower snowpack are generally well-settled and strong. Basal facets lurk in shallow snowpack areas, but we've received no recent reports of associated instabilities.

Regions covered