Avalanche forecast

Northwest Coastal

Jan 17 – 18, 2014Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    New snow and wind will likely set up reactive slabs, especially in lee and cross-loaded terrain in the alpine. Given the recent history of large avalanches, there is a chance that a small avalanche triggered near the surface could step down.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    4–7
    A weak layer of facets/depth hoar at the base of the snowpack has been responsible for some recent very large avalanches. The likelihood of triggering this layer is now considerably reduced, but the consequences associated with this layer are huge.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

A fast moving front will spread some precipitation Friday night and Saturday before the ridge of high pressure rebuilds on Sunday..Saturday: 10-15 cm new snow expected with freezing levels around 1000 m. Ridgetop winds 50-70 kméh from the south.Sunday and Monday: Dry, with a mix of sun and cloud. Freezing levels around 800 m. Winds light southwesterly.

Avalanche Summary

There was an avalanche cycle the ended on Wednesday producing avalanches up to size 4 on all elevation and on all aspects. Most of these avalanches ran on the early January surface hoar layer buried under the storm snow at treeline and below treeline; some of the larger ones ran on the deep persistent basal facet layer in the alpine in the Northern part of the region.

Snowpack Summary

Recent warm temperatures have settled the recent storm snow that ended around 13-14th January, which was previously very reactive on a layer of surface hoar (particularly between 900 and 1400 m) buried around 1 m deep. Weak basal facets near the base of the snowpack were also reactive during this time, particularly in the north of the region. These are found in the alpine and at treeline under over 2 m of snow in some areas. The deep persistent layer at the base of the snowpack is also found in the Southern part of the region, but appears to be less reactive.Extensive wind slab formed on lee and cross-loaded slopes during the SW winds associated with the last storm.

Regions covered