Bulletin d’avalanche

Cariboos

Feb 24 – 25, 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
    Very Likely - Certain
    Taille
    2–7
    Strong winds have created deep and weak wind slabs on a variety of aspects. These wind slabs are sitting on several persistent weaknesses in the upper snowpack and may release naturally or by the weight of a person.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    3–7
    Cornices have grown large and weak and may fail naturally, potentially triggering the slope below and creating a very large and destructive avalanche.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    2–6
    Up to 90cm of settling storm snow overlies several weaknesses including surface hoar and a sun crust. It may be possible to trigger avalanches in surprisingly low-angle terrain.

Confidence

Good

Weather Forecast

Tonight: Moderate snowfall - 10-15cm. The freezing level (FL) should be at valley bottom. Winds shift to moderate from the NW. Saturday: Unsettled conditions with up to 10cm of snow. FL at valley bottom. Winds are moderate from the NW. Sunday: A mix of sun and cloud. FL at valley bottom and winds ease to light from the NW. Monday: A mix of sun and cloud. FL at valley bottom.

Avalanche Summary

A natural avalanche cycle occurred on Wednesday and Thursday in most areas. Slab avalanches were reported up to Size 3 on all aspects and at all elevations. There were also several recent reports of skier triggered avalanches and remotely triggered avalanches up to Size 2.0, and a Size 2 snowmobile triggered avalanche near Blue River. The potential for triggering large avalanches will remain high throughout the forecast period.

Snowpack Summary

Strong and variable winds have created deep and weak wind slabs on a variety of aspects at all elevations. 40-90cm of storm snow has now settled into a cohesive slab and overlies the Feb. 9 weakness, which includes surface hoar and/or a crust. This surface hoar layer may be widespread in some areas, while others have reported it being confined to shady aspects at treeline and in the alpine. A melt-freeze crust can be found down 60-90cm on solar aspects at all elevations, and on all aspects below about 1600 meters. In some areas this melt-freeze crust has facets above or below it. Snowpack tests on these layers have generally given easy to moderate "pops or drops" results. There is potential for easy triggering and very wide propagation. There is some concern that large loads like cornices may trigger the Jan. 20th facet layer. Some shallow snowpack areas may continue to have a weak layer of basal facets near the ground.

Régions couvertes