Bulletin d’avalanche

Cariboos

Mar 2 – 3, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Sun
Mon
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
3 · Marqué
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–6
    Large amounts of available snow and strong westerly winds are likely to create widespread wind slabs, even at treeline. Large cornices also threaten many slopes.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–7
    Persistent weaknesses in the upper snowpack are unpredictable and tricky to manage. They may become more touchy again this weekend as storm loading and warming affects the properties of the slab above them.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–5
    New storm slab weaknesses are likely to develop as snow falls with rising temperatures. These could fail on a persistent weak layer, creating surprisingly large avalanches.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Saturday: Moderate to heavy snow (~15-35cm). Freezing level gradually rising to around 1500m. Strong westerly winds.Sunday: Continuing precipitation (~15-35mm). Strong westerly winds. Freezing level around 1500m.Monday: A cold front brings moderate to heavy precipitation with the freezing level dropping to valley bottom overnight as the front departs.

Avalanche Summary

Avalanche activity has slowed down over the last few days, with only sporadic reports of avalanches. However, these occurrences illustrate the unpredictable nature of persistent weak layers. On Friday, a skier triggered a size 2.5 slab very easily and very close to recent ski tracks, which failed on buried surface hoar. On Thursday, a cornice fall triggered a size 2 slab on a north aspect, which failed on the Feb 16. weakness. On Wednesday, numerous size 2-3 avalanches ran naturally, or with a remote trigger, on a variety of slopes. Most failed on an upper snowpack persistent weak layer. Natural avalanche activity is likely to increase again with this weekend's incoming weather.

Snowpack Summary

Snow is falling with strengthening winds and rising temperatures onto variable surfaces including surface hoar and facets. This is creating a nice recipe for new storm slab and wind slab instabilities. Persistent weak layers buried in February are a key concern at all elevations and could be triggered by storm slabs, wind slabs or sluffs, or with a light additional load (like you). Avalanches may be unexpectedly large, given the amount of fresh snow. Large cornices also loom as potential triggers for deep avalanches.

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