Bulletin d’avalanche

Purcells

Dec 31, 2011 – Jan 1, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Mon
Tue
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 - Very Likely
    Taille
    1–4
    Winds continue to redistribute storm snow into fresh wind slabs. I'd be suspect of any open area, even below treeline. Once moving, a wind slab could easily step down and trigger a large avalanche.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–6
    This layer continues to be touchy across the region. It's time to rein your terrain selection way in.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3–6
    The weight of the snowpack is pushing this layer over the tipping point in some locations. Avalanches triggered in more superficial layers have the potential to step down to this layer creating a deep and destructive avalanche.

Weather Forecast

A ridge of high pressure drifts into the area Saturday evening driving overnight temperatures into the mid minus teens. On Sunday morning high clouds steam into the region ahead of the approaching mass of warm air. Light precipitation should begin after lunch, but I'm only expecting 5 or so for the day. The bigger story with the warm front is the rise in freezing levels which could go as high as 2000 m. Winds build to moderate/strong values out of the SW Sunday. A weak cold front affects the area Monday afternoon bringing another shot of light precipitation & lowering temps/freezing levels.

Avalanche Summary

Skiers continue to remote trigger avalanches throughout the region. A few folks have been caught in avalanches too recently. Not surprisingly, explosive control work continues to trigger large avalanches to size 3.

Confidence

Fair - Freezing levels are uncertain

Snowpack Summary

Up to 100 cm of snow has fallen since Christmas bringing the total snowpack depth to around 200cm in the alpine. The holiday storm snow is now settling into a cohesive slab that sits above a very sensitive mid-December surface hoar layer. This layer continues to be easily triggered by skiers and sledders. Continued snowfall has also awoken the basil weakness near the ground on north facing slopes. This mixed bag of weaknesses has made for a very tricky avalanche situation as evidenced by the numerous accidents in the area over the last few days.

Régions couvertes