Bulletin d’avalanche

South Rockies

Feb 2 – 3, 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
    1–4
    Stiff wind slabs have formed on North through East aspects. They may be found lower on slopes in unusual places due to the strong winds. Wind slab avalanches are likely reactive to rider triggers.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–5
    Give cornices a wide berth from above and below. They usually require more space then initially anticipated. With forecast warming, cornices may fail and trigger the slope below.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–6
    The probability of triggering this layer is low in most areas, but the consequences are high. A large avalanche on this layer could be very destructive.

Weather Forecast

A strong ridge of high pressure will persist through the forecast period bringing dry conditions, sunny skies, and warmer temperatures. On Friday/Saturday freezing levels may rise to 2000m in the afternoon, then drop to valley bottom at night. Ridgetop winds should generally be light from the South. Maximum alpine temperatures near -1. Sunday brings alpine sun, valley cloud, and possibly inversions.

Confidence

Good - -1

Avalanche Summary

No new natural avalanches reported today. Our CAC field team did spend the day out, and investigated some natural slab avalanches that occurred on the 28/29th from Michel Ridge. All three slides were size 3 slab avalanches. One of the avalanches occurred on a East aspect, @ 1965m. The debris was 175m long x 20m wide, with an average depth of 2m. The avalanche consisted of a dense hard slab running on weaker facets below.

Snowpack Summary

Strong SW winds created stiff, yet reactive wind slabs on lee slopes. Cross-loading, and wind slabs are also found lower on the slopes and in unsuspecting terrain due to the strong push of the winds. Below 1700m a 4cm thick crust exists, I suspect it's from the rising freezing levels, and precipitation last Sunday. This crust is said to be supportive. Below this reports indicate the mid-pack to be fairly well settled. Deeper in the snowpack sits the mid-December surface hoar layer. This layer remains a concern for deeper releases. Basal facets and depth hoar also play a major role in this region. In Elk Valley North and the Crowsnest, the average snowpack depth at treeline is 150 cms. Elk Valley S and the Flathead the snowpack depth is closer to 2 m.

Régions couvertes