Avalanche forecast

South Columbia

Dec 11 – 12, 2013Avalanche Canada
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Avalanche danger

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

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–4
    A variety of weak layers buried in November have become less reactive, although avalanches at these interfaces would be large and destructive.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    Ongoing snowfall will add to a developing storm slab which overlies a variety of weak surfaces. Watch for increased reactivity in wind affected terrain. The new snow may also react as a loose dry avalanche in steep, sheltered areas.

Confidence

Fair - Track of incoming weather systems is uncertain on Thursday

Weather Forecast

Thursday: Moderate to locally heavy snowfall (highest amounts forecast for the Monashees) / Moderate to strong westerly winds / Freezing level at valley bottomFriday: Light snowfall / Moderate northwesterly winds / Freezing level at 1000mSaturday: Moderate snowfall / Moderate southerly winds / Freezing level at 1000m

Avalanche Summary

Numerous low density surface sluffs and soft slabs to size 2 were reported in the region reacting in response to recent storm loading. In recent days a size 2 skier-triggered slab avalanche released on the late-November interface on a north aspect 40 degree slope at 1900m. I would expect ongoing storm instabilities with weather forecast for Thursday.

Snowpack Summary

Moderate to locally heavy amounts of low density snow now overlie generally faceted surfaces that formed during the recent cold snap. At the same buried interface you may find small surface hoar on sheltered slopes or windslabs in exposed terrain. The developing storm slab is likely to become more reactive as slab properties increase with ongoing snowfall, warmer temperatures and wind.Professionals are still keeping their eye on the late-November interface which consists of sun crusts on steep south facing slopes and surface hoar in sheltered areas. Although this layer seems to have become less reactive, it may be triggered on steeper, unsupported terrain or by the weight of the new snow.At the base of the snowpack is a crust/facet combo that formed in October. About 60cm above the ground is a surface hoar layer which formed in early November. These layers have become generally inactive; however, residual risk of large, destructive avalanches exists, especially in areas with a thinner snowpack.

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