Avalanche forecast

Northwest Coastal

Mar 31 – Apr 1, 2018Avalanche Canada
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Avalanche danger

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

Storm slabs exist in the south of the region from recent snowfall. This overlies a couple touchy weak layers. Be cautious on southerly aspects when the sun is out. Conservative decision-making is recommended.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    A weak surface hoar layer buried about 50 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 - Likely
    Size
    1–2.5
    Recent snowfall of up to 40 cm in the south of the region have formed reactive storm slabs.  Slabs may be more reactive on sunny and lee slopes. Observe for signs of instability within the snow, such as cracking, whumpfing, and avalanche activity.

Confidence

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

Weather Forecast

SUNDAY: Early-morning snowfall then mostly sunny, accumulation 2 to 5 cm with possible localized higher amounts from convective flurries, light northeasterly winds, alpine temperature -9 C, freezing level 600 m.MONDAY: Mostly cloudy with afternoon snowfall, accumulation 1 to 3 cm, light southerly winds, alpine temperature -9 C, freezing level 600 m.TUESDAY: Mostly cloudy with early-morning snowfall, accumulation 5 to 10 cm, light southwesterly winds, alpine temperature -10 C, freezing level 500 m.

Avalanche Summary

On Friday, a natural cycle within the recent storm snow occurred, failing as storm slabs and loose dry avalanches. They were small to large (size 1 to 2), on all aspects, and at all elevations. See this MIN report to observe some of the avalanches.Previously in the 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

Thursday’s storm dumped 30 to 40 cm of snow in the south of the region, such as around Terrace and Shames.  There is now about 70 to 90 cm of storm snow that overlies two layers of surface hoar, which were buried early- and mid-March. At low elevations, the storm snow sits on a melt-freeze crust.Dormant weak layers exist deeper in the snowpack.  Layers of crusts, facets, and isolated surface hoar from mid- and late-February are buried 100 to 150 cm.  Near the bottom of the snowpack, weak and sugary facets exist in shallower parts of the region, such as the far north.

Regions covered