Bulletin d’avalanche

Northwest Inland

Nov 24 – 25, 2017Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré

Points saillants

Even as storm slabs begin to stabilize, the presence of a more deeply buried weak layer continues to demand conservative terrain selection.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    Recent stormy weather formed storm slabs that may remain reactive on Saturday. These storm slabs are widespread but you can expect them to be especially reactive at higher elevations and in wind affected areas with more variable snow distribution.
  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3
    A crust that formed in October exists near the base of the snowpack and a layer of weak, sugary snow has developed above it. This layer may react to a heavy trigger such as a storm slab release. This would produce a large, destructive avalanche.

Confidence

Low - Due to the number of field observations

Weather Forecast

Saturday: Mainly cloudy with isolated flurries and a trace to 5 cm of new snow. Light to moderate southwest winds. Alpine temperatures around -7.Sunday: Cloudy with flurries bringing approximately 7 cm of new snow. Moderate southeast winds. Alpine temperatures of -5.Monday: Mainly cloudy with isolated flurries and a trace of new snow. Strong southwest winds. Alpine temperatures around -6.

Avalanche Summary

One report from Wednesday discussed several estimated Size 2.5-3 avalanches observed on the Kathlyn face of Hudson Bay Mountain. No other new avalanches have been reported, which likely owes more to a lack of observers than a lack of avalanche activity and potential. Please post your observations to the Mountain Information Network. (MIN)

Snowpack Summary

Snowpack depths over the region are above average for late November, with approximately 150 cm of settled snow present at treeline elevations and above. Stormy weather over the mid-week delivered about 35 cm of new snow to the region, forming storm slabs which are expected to be particularly reactive in open terrain where wind effects are more pronounced. Mid-treeline and lower elevations did receive some precipitation as rain toward the end of the most recent storm, but his thin rain layer is not expected to offer much bridging strength to the snowpack. About 20-30 cm of recent storm snow lies below this week's accumulations and above the widespread late October crust. This October crust is present near the base of the snowpack at all elevations and features a layer of weak, sugary grains above it. This "crust/facet combo" layer remains an ongoing concern for step-down potential from large triggers such as a storm slab release. The crust is less of a concern below treeline where it is broken up by vegetation near the ground.

Régions couvertes