Avalanche forecast

South Columbia

Mar 4 – 5, 2013Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    New weak cornice growth may fall off naturally, or with light additional loads and/or solar warming.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–7
    A weak layer of surface hoar and/or a crust is now down 100 cm or more. This weakness has been susceptible to remote triggering and has been reported from all elevations and aspects.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–6
    We may see another round of natural avalanche activity when slopes start receiving direct sun. Human triggering remains a concern as the snowpack adjusts to it's new load and storm slab avalanches may step down to the buried surface hoar.

Confidence

Fair - Due to variable snowpack conditions for the entire period

Weather Forecast

Synopsis: A ridge of High pressure over the Eastern Pacific will provide a mix of sun and clouds with some chance of light precipitation for the next 2-3 days. Winds are expected to be light Northeasterly and alpine temperatures should be around -11.0.

Avalanche Summary

Reports of a widespread natural avalanche cycle up to size 3.0 during the recent storm. Some avalanches were reported to have released in the storm snow down about 40 cms and resulted in avalanches up to size 2.0. It may take a couple of days to decide if the recent storm cleaned out most of the weak February 12th surface hoar, or if the weak layer will continue to be triggered by human activity.

Snowpack Summary

The storm snow is expected to settle and bond to the old surface over the next few days. A crust has formed up to about 1800 metres where the recent warm storm had turned to rain. In the alpine there may be a weak layer in the storm snow that was developed during a temperature change in the middle of the storm. Below the storm snow lies a highly reactive weak layer of surface hoar (and/or a crust) which was buried on February 12th. Deeper persistent weak layers from early February and late January continue to show planar failures when moderate to hard forces are applied in snow pack tests. In particular, in the Monashees, a rain crust buried down 150 cm has been responsible for a couple of recent large, surprising avalanches.

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