Bulletin d’avalanche

Northwest Coastal

Mar 6 – 7, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Thu
Fri
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Generally lurking below ridgecrests, behind terrain breaks, and in gullies. Wind slabs are very touchy and there is still a lot of snow available for transport.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–5
    A persistent weak layer of crusts, facets, and surface hoar is buried down close to metre. The likelihood of triggering this layer is decreasing, but the consequences of an avalanche failing on this layer are high.

Confidence

Good

Weather Forecast

20cm of new snow is expected by Wednesday morning with continued flurries, moderate winds, and rising freezing levels throughout the day. A warm front should move in from the Pacific on Wednesday night bringing strong southerly winds, freezing levels as high as 1000m, and heavy precipitation with up to 60mm by Thursday evening. Expect a brief reprise Friday morning, before the associated old front moves down from the north Friday midday with continued snowfall, strong southwesterly winds and freezing levels back down to valley bottoms.

Avalanche Summary

There was very little avalanche activity reported on Monday, despite the strong solar radiation. Recent reports include several natural wind slab avalanches up to Size 2 on north through northeast aspects near ridge crests, with one Size 2.5 on a cross-loaded west aspect. Natural loose snow avalanches up to Size 1.5 were also observed in steep and confined terrain but they ran far.

Snowpack Summary

Strong westerly winds are keeping wind slabs fresh and weak on lee aspects and isolated afternoon down flow (katabatic) winds were reported to have deposited new wind slabs primarily in gully features and on northerly aspects. The early February persistent weak layers seem to be bonding, but remain a concern at higher elevations with heavy triggers such as cornice falls. While below treeline persistent slabs are reactive to human triggers on isolated sheltered steep terrain where buried surface hoar is preserved. Surface hoar buried at the beginning of March remains unreactive due to limited slab formation.

Régions couvertes