Bulletin d’avalanche

Northwest Coastal

Dec 12 – 13, 2012Avalanche Canada
Voir sur la carte
Archivé · expiré 14 years ago

Danger d’avalanche

Fri
Sat
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
Ouvrir la carte complète

Points saillants

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–5
    Storm slabs are likely to be encountered on many slopes. Be alert for new and buried wind slabs behind ridges and ribs. Storm/wind slabs could step down to trigger a persistent weakness.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–8
    A deeply buried facet/crust weakness exists. Very large and destructive avalanches are possible, and may be triggered by  heavy loads such as cornice fall or a storm slab stepping down.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

A series of frontal systems will affect the coast for the next few days. The timing is a bit uncertain but the general pattern is stormy.Thursday: Strong W winds. Alpine temp -4. Moderate snow (locally heavy).Friday: Moderate to strong W winds. Alpine temp -6. Light to moderate snow.Saturday: Light winds. Alpine temp -10. Moderate to heavy snow.

Avalanche Summary

A natural cycle occurred on Tuesday with avalanches to size 2.5 running in steep terrain at treeline and alpine elevations. Explosives testing produced several very large (size 3-4) slabs on northerly aspects near Stewart. These failed on basal facets and/or glacial ice and were up to 4 m deep and 250-300 m wide. Recent storm/wind slabs above 1600 m which were triggered by cornice fall or explosives also stepped down to basal facets. Low elevation steep terrain was also shedding numerous small, moist loose avalanches during Tuesday’s warming.

Snowpack Summary

Storm snow instabilities are likely for the next few days. New and buried wind slabs are widespread and exist on a variety of alpine and exposed treeline slopes due to variable winds. A rain crust is now buried by new snow at low elevations. A November facet/crust layer can be found near the base of the snowpack. Very large releases are still occurring on this layer with a heavy trigger, such as storm slabs stepping down, explosives, or cornice fall.

Régions couvertes