Bulletin d’avalanche

Northwest Coastal

Mar 6 – 7, 2013Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Fri
Sat
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Points saillants

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    On Tuesday outflow winds produced thin new wind slabs behind terrain breaks, primarily on southwest to northwest aspects.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–6
    Cornices may fail naturally with daytime warming and sunshine this week. These could potentially trigger a slab on the slope below.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    Warm sun is weakening surface snow, particularly on steep south-facing slopes. Loose wet avalanches can entrain a surprising amount of mass as they travel.

Confidence

Fair

Weather Forecast

Thursday: Clear skies / Light south winds / Freezing level at 600mFriday: Mix of sun and cloud / Light south winds / Freezing level at 900mSaturday: Light snowfall / Light southwest winds / Freezing level at 900m

Avalanche Summary

Recent reports include a few small natural wind slabs in steep lee terrain in response to northerly outflow winds. A few natural cornice failures, ice falls, and glide slab releases have also been reported. One cornice fall observed just north of Terrace triggered a size 3 slab avalanche that is suspected to have released on the late February weak layer. This event could have been a few days old.

Snowpack Summary

Outflow winds (from the north and east) have created new hard and soft wind slabs in exposed lee terrain. In sheltered areas the snow surface consists of facets, surface hoar, or a sun crust/ moist snow on south facing slopes. A layer of surface hoar, facets and/or a crust is buried down 50-90 cm, but most operators report a good bond at this interface. Watch out for cornices, as they are large and fragile. Several large cornice falls have been reported over the past few days. Most have not triggered slabs on the slopes below, however at least one triggered a very large avalanche. The mid snowpack layers are generally well settled and strong. Facets at the base of the snowpack have resurfaced as a concern now that spring is on the doorstep and full-depth releases are becoming more likely (primarily in the northern part of the region).

Régions couvertes