Bulletin d’avalanche

Kootenay Boundary

Jan 5 – 6, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Sat
Sun
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    Fresh wind slabs are lurking below ridge crests, behind terrain features, and in cross-loaded gullies. New cornices are also weak.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–5
    Persistent weaknesses remain susceptible to human-triggers, including remote triggering.

Confidence

Good - -1

Weather Forecast

Friday and Saturday: Generally dry, with freezing levels near valley bottoms and light winds. Light snowfall expected overnight Saturday into Sunday accompanied by moderate to strong westerly winds.

Avalanche Summary

Recent activity on the mid-December surface hoar includes a snowcat remotely triggering a 70cm deep Size 2 slab avalanche from 10m away on a log-haul landing in a cutblock. Recent storm snow overlying a crust is also highly reactive to human triggers with slope-cuts producing numerous loose snow and 10-30cm thick slab avalanches up to Size 1.5.

Snowpack Summary

New snow and gusty winds are keeping wind slabs and cornices fresh and weak, and in some places buried old wind slabs are a concern. A lightly buried thin crust extends into treeline elevations. Compression tests have been producing easy to moderate sudden results on the mid-December surface hoar, down 30-80cm, and propagation tests, whumpfing, and remote triggering suggest that avalanches associated with this persistent slab have a high propensity to propagate over large areas. Other weaknesses within the slab create the potential for step-down avalanches. Basal facets and depth hoar remain a concern in shallow rocky areas.

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