Avalanche forecast

Northwest Inland

Dec 31, 2016Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Cold, northwesterly winds mark a change in wind direction, which will set up fresh wind slabs in new locations in exposed terrain.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    Variable winds will redistribute light amounts of new snow into fresh wind slabs. Watch for areas that were previously scoured and may become reverse-loaded as the winds switch direction.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–3
    40-60 cm of recent snow sits above a weak, faceted lower snowpack. This fundamentally weak snowpack structure supports human-triggered avalanches from places like convex slopes in shallow areas, and is likely to persist for some time.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Friday evening: 3-12cm of new snow / Extreme westerly winds / Alpine temperatures of -3Saturday: Lingering flurries in the morning with clearing in the afternoon / Extreme northerly winds / Alpine temperatures of -10Sunday: Clear skies / Extreme northerly winds / Alpine temperatures of -10Monday: Clear skies / Moderate northerly winds / Alpine temperatures of -3

Avalanche Summary

No new avalanches have been reported. Wind slabs will likely remain touchy throughout the forecast period, as sustained winds will redistribute the new low density snow. The additional load of new snow will also keep deeper persistent weak layers reactive, making it possible to trigger larger avalanches.

Snowpack Summary

Snowpack depths in this region are still shallow - around 1 m or so, meaning there are a lot of weak sugary facets in the snowpack at this time. Recent storm snow has been redistributed by the wind, and wind slabs are widespread behind exposed ridges. Where hard wind slabs overlie weak facets, the structure is ripe for human-triggered avalanches. In addition to the sugary facets, you may find a layer of feathery surface hoar (up to 15 mm in sheltered areas), buried around 15-25 cm below the surface. There is another weak layer that formed during the early December cold snap which is now about 40-60 cm deep. A crust from mid-November may be found close to the bottom of the snowpack nestled in amongst the facets. We don't have a lot of information about these layers, but it's worth noting the layer responsible for most of the large avalanches during the big storm just before Christmas was the mid-November rain crust.

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