Bulletin d’avalanche

Kootenay Boundary

Jan 19 – 20, 2015Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

The recent storm snow sits on a weak layer and touchy conditions may persist for a few days. The deep mid-Dec layer remains a concern and isolated avalanches continue to step down to this layer.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–4
    The recent storm snow sits on a layer of touchy surface hoar. Recent strong SW winds have loaded leeward features in the alpine and in isolated areas at treeline. Loose sluffing is a concern in steep terrain features.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–6
    The mid-Dec weak layer should remain on your radar as it still has the potential to produce large avalanches. Smaller avalanches or cornice falls have the potential to trigger a deeper weakness.

Weather Forecast

A ridge of high pressure should keep the region dry and mostly sunny for Tuesday-Thursday. On Tuesday and Wednesday, freezing levels should reach around 1000m during the day and fall to valley bottom overnight. On Thursday, an inversion is forecast and above-freezing air in the alpine is possible. Alpine winds are expected to remain light for Tuesday and Wednesday but are forecast to increase to moderate on Thursday.

Confidence

Fair

Avalanche Summary

On Sunday, a skier remotely triggered a size 2 avalanche on the mid-Dec weak layer down around 50cm on an east aspect at treeline. A ski cut produce a size 1 avalanche on the mid-Jan weak layer down around 25cm. Explosives triggered several storm slabs up to size 2 on all aspects. On Saturday, a skier remotely triggered a size 1 avalanche on the mid-Dec layer down around 40cm. Natural avalanche activity is generally not expected on Tuesday but remains possible in isolated areas. Human-triggering is likely in wind loaded areas and steep terrain features, especially where surface hoar underlies the recent storm snow.

Snowpack Summary

30-40cm of recent storm snow sits on the mid-Jan surface hoar layer. In many places the surface hoar sits above a thin crust that can be found up to about 1900m on north aspects and all the way to ridgeline on south aspects. A deeper crust/surface hoar combo buried in mid-December continues to be a concern. This layer can typically be found down 70-100cm. The reactivity of this persistent weak layer appears to have become isolated but still has the potential for large, destructive avalanches in some areas. The layer appears has been the most reactive at and just below treeline.

Régions couvertes