Avalanche forecast

Northwest Coastal

Apr 1 – 2, 2018Avalanche Canada
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Avalanche danger

Tue
Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate

Highlights

Storm slabs overlie a couple weak layers, which have produced large and destructive avalanches. Observe for signs of instability within the snow before committing yourself into avalanche terrain, such as cracking, whumpfing, and avalanche activity.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    A weak surface hoar layer buried 50 to 90 cm has produced large slab avalanches that have propagated widely. It is best to avoid sheltered north to easterly slopes, where this layer is most likely to be a problem.
  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5
    Although storm slab activity has decreased, it is still possible to trigger them. Slabs may be more reactive on lee slopes where the snow has more slab properties.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

MONDAY: Mostly cloudy with afternoon snowfall, accumulation 1 to 3 cm, light southwesterly winds, alpine temperature -10 C, freezing level 500 m.TUESDAY: Cloudy with snowfall, accumulation 10 to 15 cm, light southwesterly winds, alpine temperature -10 C, freezing level 500 m.WEDNESDAY: Mostly cloudy with light snowfall, accumulation 1 to 3 cm, light southerly winds, alpine temperature -9 C, freezing level 600 m.

Avalanche Summary

On Saturday, a large persistent slab avalanche was reported in the north of the region, failing on the early-March weak layer described in the Snowpack Discussion.  It failed on an easterly aspect around treeline.  Otherwise, there was further evidence of the natural cycle that occurred on Friday within the recent storm snow, with storm slab and loose dry avalanches.  They were small to large (size 1 to 2), on all aspects, and at all elevations.Last week, large persistent slab avalanches were reported at all elevation bands, on east to northeast aspects.  These were failing on the early- and mid-March layers described in the Snowpack Discussion.

Snowpack Summary

Expect to find a surface crust on southerly aspects from the weekend’s clear skies.In the south of the region, there is about 70 to 90 cm of storm snow from last week that overlies two layers of surface hoar, which are most prominent on north to easterly aspects and were buried early- and mid-March. In the north of the region, these layers are around 40 cm deep.  At low elevations, last week’s storm snow sits on a melt-freeze crust.Near the bottom of the snowpack, weak and sugary facets exist in shallower parts of the region, such as the far north.

Regions covered