Bulletin d’avalanche

Purcells

Jan 1 – 2, 2015Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

Sat
Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Conditions are variable across the region. Cautious route-finding and conservative decision-making are essential.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    Recent strong winds have left wind slabs behind on a variety of slopes. These may become hidden under a dusting of new snow.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–5
    A buried surface hoar/ crust layer demands respect. It has been easy to trigger persistent slabs with light loads (like a person). This layer is down about 30-50 cm in most areas, but may be deeper where wind slabs have developed.

Confidence

Fair - Wind effect is extremely variable

Weather Forecast

Snowfall is expected to increase overnight and into Friday (5-10 cm by Friday afternoon). Winds are forecast to be moderate from the SW to NW. Freezing level at valley bottom. Snowfall becomes light on Saturday before a second pulse of snow arrives late on Sunday.

Avalanche Summary

Explosives control on Tuesday produced several avalanches up to size 3. Some of these failed on persistent weak layers, while others only involved surface snow. Natural wind slabs were also observed near ridge tops over the last couple of days.

Snowpack Summary

Variable wind slabs exist in some areas. A spotty thin layer of surface hoar was buried on December 27th by about 5-10 cm of light dry snow. As more snow accumulates, this interface could become one to watch. A persistent surface hoar/crust weak layer from mid-December is now down about 40-60cm. Recent snowpack tests show moderate pops-type results here, indicating the potential for avalanches to propagate on this layer. This persistent slab problem is reasonably widespread across the region and is not expected to improve quickly. A deeper crust/facet layer which formed early in the season may still be triggerable from thin or rocky snowpack areas.

Régions couvertes