Avalanche forecast

South Rockies

Jan 4 – 5, 2012Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    Wind slabs can be found on North through Southeast aspects. Cross-loading is possible on open slopes oriented parallel to the wind. You may find wind slabs further down the slope or on open wind exposed areas below treeline.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–6
    Warm temperatures may consolidate the snow above the surface hoar into a slab that may propagate wide avalanches. This mid-December surface hoar/ facet layer is found mainly in the Western parts of the region.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

As the cold front sweeps through the Southern interior on Wednesday afternoon we will see cooling temperatures and light-moderate precipitation amounts. Wednesday Night: Snow amounts up to 15cms. Ridgetop winds 55-85km/hr from the West. Alpine temperatures near -4. Freezing levels down to 700m. Thursday: Snow amounts near 5cms in the morning. Mainly sunny skies in the afternoon. Freezing levels around 400m. Ridgetop winds 45-70km/hr from the SW. Friday/Saturday: A building ridge will provide cool, dry seasonal conditions.

Avalanche Summary

Two separate skier triggered avalanches were reported Tuesday from the Hartley Creek drainage-Fernie. Both being slab avalanches size 1 on a NE aspect and the other on an East aspect, between 1850m-2150m. Both avalanches were reported as soft slabs failing on the mid-December layer. No injuries reported. On Monday a skier triggered a size 2 slab avalanche in the Harvey Pass area. Initially a wind slab from the ridgecrest was triggered, then stepped down 55cms to a weak surface hoar/ facet layer beneath the surface. Please visit our incident report database on our website for more details @ avalanche.ca.

Snowpack Summary

The average HS (height of snow) in the Crowsnest North is 120cms and the Crowsnest South has 150cms. In the alpine and exposed slopes at treeline the windward aspects have been stripped of snow, and the lee slopes have widespread stiff wind slabs. As we move further West into the Elk Valley North the HS is an average of 130cms. The Elk Valley South sits at 170cms. Weak buried surface hoar layers can be found on North-NE slopes at treeline and below down approx. 30-40cms. In the Flathead the avg. HS is 170cms. This area also sees buried surface hoar on N-NE slopes. The CAC Field team headed to Harvey Pass on Tuesday and completed a fracture line profile on a skier triggered avalanche. A stiff wind slab was triggered and stepped down 55cms to the mid-December surface hoar/facet layer. Compression tests done showed easy results with sudden planar characteristics. This shows this layer is still touchy to human triggers. The mid pack is generally well consolidated. At the bottom of the snowpack a variable facet/ crust/ facet sandwich is located with depth hoar up to size 5 below the crust, and facets size 2 above.

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