Bulletin d’avalanche

South Columbia

Dec 24, 2017Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Slab formation remains the critical factor for avalanche danger under current conditions. The best and safest riding will be in soft, unconsolidated snow.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    Shifting winds since the storm have been redistributing new snow into wind slabs on a variety of aspects. The freshest slabs are the result of recent northerly winds. Keep this reverse loading pattern in mind as you gain elevation.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3
    The December 15 interface will likely be most reactive where the new snow has settled into a slab over buried surface hoar. Use extra caution around steeper, sheltered slopes at treeline and below - especially if you see signs of slab formation.

Confidence

Moderate -

Weather Forecast

Sunday: A mix of sun and cloud. Light west winds. Alpine temperatures around -14.Monday: Mainly cloudy. Light northeast winds. Alpine temperatures around -17Tuesday: A mix of sun and cloud. Light southwest winds. Alpine temperatures around -17.

Avalanche Summary

Reports from Friday included observations of numerous wind slab releases, mainly Size 1, with a couple of Size 2. These were initiated by a mix of natural and skier triggers on varied aspects above 2000 metres. Persistent slab activity to Size 1 was also reported at lower elevations. Reports from the previous few days included explosives controlled and natural storm snow avalanches to size 2.5 in the alpine and treeline. There were also several reports of skier accidental and skier remote (triggered from a distance) avalanches to size 1.5 at and below tree line. Persistent slab avalanche danger can be expected to persist in areas where our recent snow consolidates into a slab above the December 15 interface. In areas where new snow has not yet consolidated into a slab, expect continued potential for triggering loose dry avalanches in steep terrain.

Snowpack Summary

Stormy weather over the past week has brought 50-80 cm of new snow to the region. The new snow lies over a wide variety of old surfaces, including large surface hoar (weak, feather-like crystals), hard crusts formed by sun or wind, and sugary facets. The bond at this old snow interface is of critical importance in areas where the overlying snow has consolidated into a slab. The most concerning areas areas will be those that have seen previous surface hoar development, such as sheltered areas at and below tree line and sheltered northerly aspects in the alpine. Additionally, any steep solar aspects where surface hoar may be sitting on sun crust should be considered areas where this weak layer may be more likely to trigger. A crust which was formed by rain in late November is a major feature in the snowpack and is down approximately 90-120cm at tree line elevations. Snowpack tests suggest the snow above is currently bonding well to it.

Régions couvertes