Avalanche forecast

South Columbia

Feb 18 – 19, 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

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–5
    New wind slabs have developed at higher elevations. Older wind slabs may be buried by the new snow and may be difficult to locate.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–6
    There are older layers of buried surface hoar and crusts that are unlikely to be triggered by the weight of a skier or sledder, but may be triggered by large additional loads like cornice fall or wind/storm slab avalanches in motion.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–5
    New snow has added to the load of the recent storm snow. This storm slab is expected to continue to be reactive above a weak layer of surface hoar and sun crusts.

Confidence

Fair - Due to variable snowpack conditions for the entire period

Weather Forecast

Overnight and Tuesday: A weak upper trough is forecast to move across the region tonight bringing moderate Southwest winds. The trough should continue to influence the interior regions on Tuesday. Expect mostly cloudy conditions with light winds and very light precipitation. Freezing levels are expected to rise to about 1000 metres during the day.Wednesday: The next weak ridge of high pressure should move into the interior ranges to fill in behind the trough as it exits into Alberta. Expect gradually clearing skies, light winds and freezing levels near the valley bottoms. There is a chance of some strong solar radiation in the afternoon.Thursday: Another trough is expected to drift into the interior from the coast. Snow fall amounts are un-certain at this time.

Avalanche Summary

There was a lot of avalanche activity reported from Sunday. Skier controlled, skier accidental, and natural avalanches up to size 2.5 on various aspects and elevations. All of the avalanche activity reported released on the weak February 12th buried surface hoar layer.

Snowpack Summary

New snow has added to the recent storm slab above the February 12th weak surface hoar layer. This layer is now buried down about 20-50 cms depending on where you are in the region. This variable storm slab is also above a sun crust on Southerly aspects. New wind slabs developed at higher elevations due to the new snow and wind during the storm. These soft new wind slabs may be hiding stiffer wind slabs that are a couple of days older. Deeper persistent weak layers from early February and late January continue to show planar failures when moderate to hard forces are applied to snow profile tests. These deeper layers have not been reactive to the loads associated with recreationalists, but they may be triggered by large loads like an avalanche in motion, or a cornice fall.

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