Avalanche forecast

Northwest Coastal

Mar 16 – 17, 2017Avalanche Canada
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Avalanche danger

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

Wind slabs have emerged as the primary avalanche problem in the region, but they aren't the only one. Deeper in the snowpack, our persistent slab problem lingers on.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–3
    Forecast flurries will combine with strong south to southeast winds and form fresh wind slabs on Friday. Use increasing caution as you enter wind affected terrain expect touchy new slabs in the lee of exposed terrain features at treeline and above.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–4
    A persistent weak layer from late February is buried up to a metre deep and continues to show reactivity in snowpack tests. Potential still exists for a rider to directly trigger this layer or for a smaller wind slab avalanche to act as a trigger.

Confidence

Moderate -

Weather Forecast

Thursday night: Flurries bringing 10-15 cm of new snow. Moderate to strong southeast winds.Friday: Flurries bringing approximately 10 cm of new snow. Moderate to strong south winds. Freezing level to 600 metres with alpine temperatures around -7.Saturday: Mainly cloudy with scattered flurries and a trace of new snow. Light to moderate southwest winds. Freezing level to 400 metres with alpine temperatures around -7.Sunday: Cloudy with scattered flurries and a trace of new snow. Moderate southwest winds. Freezing level to 500 metres with alpine temperatures around -6.

Avalanche Summary

Wednesday's reports include further observations of the widespread natural avalanche cycle that occurred on Tuesday. Natural wet slab avalanches ran up to size 2.5 and loose wet avalanches ran up to size 1.5. Below treeline elevations were especially active in the north of the region. Reports have been limited due to poor visibility and travel conditions.

Snowpack Summary

Recent stormy weather has blanketed the region with storm slabs that are approximately 30-60 cm deep, with much deeper areas where the wind has transported the recent snow. As these slabs have formed a bond to the surface, ongoing winds and light new snow accumulations have seen our primary hazard transition to wind slabs. At treeline and above, new snow and wind have been loading and stressing a weak interface from February composed of facets, crust, and surface hoar buried over a metre deep. This layer was active prior to the storm and remains an ongoing concern. After below zero temperatures on Wednesday night, a surface crust has likely formed over moist or wet snow previously reported at 1100 metres and below.

Regions covered