Bulletin d’avalanche

Northwest Inland

Jan 9, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Weak, sugary snow at the bottom of the snowpack remains a primary concern. This is especially true in large, steep, and rocky alpine features with variable snowpack depths.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2
    Forecast strong to extreme easterly winds may form wind slabs in unusual places such as open areas below treeline.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    This is a low probability, high consequence scenario and requires a conservative approach to larger terrain features. Avoid likely trigger spots such as steep and rocky areas with a shallow snowpack.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

MONDAY: Mix of sun and cloud, strong to extreme easterly ridgetop winds, and temperatures around -20 C.TUESDAY: Mostly sunny with cloudy periods, moderate to strong northeasterly ridgetop winds, and temperatures around -15 C.WEDNESDAY: Mostly sunny with cloudy periods, moderate northeasterly ridgetop winds, and temperatures around -10 C.

Avalanche Summary

Over the past week there have been a couple natural deep persistent avalanches to size 3.5. These are large, destructive avalanches that failed on sugary facets at the bottom of the snowpack and ran long distances.

Snowpack Summary

10-20 cm of recent snow with northerly winds have likely created fresh wind slabs sitting on top buried surface hoar and/or facets. Snow depth at treeline varies from about 1 m in most areas to 2 m in deeper snowpack areas in the south and west of the region, and up to 250 cm in the alpine. The shallow snowpack areas mostly consist of weak facetted or sugary grains beneath hard slabs. These hard slabs may produce surprisingly long fractures resulting in large avalanches, and in some instances they may step down to weak snow crystals near or at the ground. In addition to the facets, a thick layer of buried surface hoar may be found 30-40 cm below the surface. There is another persistent weakness that formed during the early December cold snap which is now about 50-70 cm deep. A crust from mid-November may be lurking close to the ground nestled in amongst the facets.

Régions couvertes