Bulletin d’avalanche

South Columbia

Mar 26 – 27, 2013Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Thu
Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    2–6
    Natural cornice falls are a concern during daytime warming. Cornices may also be triggered easily by traveling near them. Slopes with corniced entrances, or exposed to cornice falls should be avoided with these conditions.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–6
    The March 10th weak layer of surface hoar is buried down more than a metre in most places. Large loads like cornice falls may trigger this deeply buried weak layer.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–4
    Pockets of wind slab from localized wind, including down-flowing katabatic wind, could be rider triggered. Periods of strong solar radiation may cause loose moist or wet snow to fall out of very steep terrain.

Confidence

Good

Weather Forecast

The ridge of High pressure is expected to continue to influence the interior ranges for the next few days. As the ridge weakens we may see high cloud reducing the exposure to strong solar radiation. Nights are expected to continue to be clear and cool. Freezing levels in the North should rise during the day to about 1800 metres, and to about 2000 metres in the South.

Avalanche Summary

Natural cornice failures and wet-loose avalanche up to Size 2.5 continue to be reported from throughout the region. This avalanche activity is expected to continue with warm and sunny weather throughout the forecast period.  On Sunday, a skier accidentally triggered a Size 2.0 persistent slab avalanche on a west through southwest facing alpine slope in Glacier National Park, that resulted in one fatality. The avalanche failed on surface hoar sitting on a crust that was buried on March 11th.

Snowpack Summary

Surface faceting and surface hoar growth has been prevalent on shady slopes and at upper elevations, while the surface snow on sun-exposed slopes and at lower elevations has been subject to daily melt-freeze cycles. Cornices are reported to be very large and weakly bonded. Wind slabs are reported to be strengthening, but may continue to be sensitive to human-triggers. The weak layer of buried surface hoar from March 10th is down more than a metre in most places, and is giving variable results in snow profile tests. However, this deep persistent weakness remains a concern because of the potential for very large avalanches particularly with heavy triggers such as cornice falls.

Régions couvertes