Avalanche forecast

Northwest Coastal

Apr 5 – 6, 2013Avalanche Canada
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Archived · expired 13 years ago

Avalanche danger

Sun
Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    New winds slabs may form in exposed lee terrain and cross-loaded features. Triggering may be possible in steep terrain.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–6
    Large developed cornices loom over slopes. A cornice fall has the potential to initiate large avalanches.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–5
    Recent reports of remote triggering suggest the March 9th surface hoar layer is still touchy in some areas. Where it is still reactive, avalanches can be large and potentially destructive.

Confidence

Good

Weather Forecast

Synopsis: A weak frontal system is forecast to move through on Friday night and into Saturday. Conditions should begin to dry out and clear on Sunday and Monday as a ridge of high pressure forms.Saturday: Cloudy with light snow – 5-10 cm. The freezing level is around 1000 m. Winds are moderate from the south-southeast. Sunday: Sunny breaks. The freezing level rises to 1400m during the day and winds are light from the north. Monday: A mix of sun and cloud. The freezing level is steady around 1400-1500 m.

Avalanche Summary

There were no reports of new avalanches on Thursday. A few new wet loose or slab avalanches were reported at lower elevations on Wednesday. Many of these were releasing on the ground and most were from steep solar aspects. Glide cracks and cornices continue to fail with some regularity.

Snowpack Summary

5-10 cm of new snow sits on a variety of old snow surfaces including a melt-freeze crust, moist snow, sugary facets, and wind affected snow. Pockets of wind slab could develop in exposed lee terrain over the next several days. Between 50-75cm below the surface is layer of surface hoar buried on March 9th which is variably reactive. In some areas it is stubborn and requires a significant trigger. In other areas the layer is still well preserved showing sudden planar or sudden collapse test results, and remains a primary concern among some professional operators.The mid snowpack is generally well settled and strong. Having said that, basal facets may resurface as a concern with spring warming, particularly in the north of the region. Cornices are large and untrustworthy.

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