Avalanche forecast

South Rockies

Feb 4 – 5, 2012Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–6
    Cornices are large, unsupported and particularly weak with current warming. Give cornices a wide berth from above and below.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–6
    Deep persistent slabs may be triggered with a larger trigger (cornice fall, sled). They may also be triggered by solar warming

Confidence

Fair - Freezing levels are uncertain for the entire period

Weather Forecast

A firmly embedded ridge of high pressure will continue to dominate the region bringing clear skies and light southerly winds throughout the forecast period. An inversion with above freezing alpine temperatures will persist on Sunday, but will give way to a gradual cooling pattern forecast for Monday and Tuesday.

Avalanche Summary

In the Bull River area on Saturday widespread natural activity to size 3 was reported on sun-exposed aspects in the alpine. On Friday, a size 3 natural slab avalanche was reported on sun-exposed alpine feature. This was thought to have ran on basal facets. In the neighboring Lizard range numerous deep releases to size 3.5 were reported on facets that formed in October. The same snowpack structure exists in many parts of the South Rockies region.

Snowpack Summary

Storm snow from the last few weeks seems, for the most part, to be fairly well settled. In the mid snowpack sits the mid-December surface hoar layer. Lately this layer has been less of a concern. At the base of the snowpack basal facets and depth hoar seem fairly widespread in the region. The big story for the weekend has been warming at higher elevations due to an inversion and solar heating. Failing cornices, loose wet snow avalanches on sun-exposed slopes and isolated deep releases on basal facets have been the big things to watch for. In Elk Valley North and the Crowsnest, the average snowpack depth at treeline is 150 cms. Elk Valley S and the Flathead the snowpack depth is closer to 2 m.

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