Bulletin d’avalanche

Northwest Inland

Dec 5 – 6, 2012Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Fri
Sat
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–4
    New storm slabs and wind slabs have formed, especially on lee slopes, gully features, and behind ridges. They may be touchy, especially sitting on an old buried weak layer (surface hoar). Rider triggering is likely.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–6
    Basal facet/crust weaknesses are often prone to remote triggering and step down avalanches. Typical trigger points include thin rocky areas. They may be difficult to trigger, but deep persistent slab avalanches are often very large.

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain on Saturday

Weather Forecast

Thursday: The region will be under the influence of a Westerly zonal flow. This will bring cooler temperatures, mainly cloudy skies and continuous light-moderate snow, alpine temps -10, ridgetop winds SE 30km/hr. Friday through Saturday: A weak low pressure system moves into the region bringing moderate snow, ridgetop winds NW 15 km/hr, and alpine temps near -11.

Avalanche Summary

Recent reports of several isolated loose dry sluffs from steep terrain features. For a bit more information in the Hankin Area, check out the Regional Forum Posts.

Snowpack Summary

Wind slab instabilities are likely to exist in the upper snowpack at treeline and in the alpine. They may be touchy to rider triggers, especially on leeward slopes and behind terrain features. Treeline depths range between 90-125 cm, but highly variable in the alpine with deep wind drifts and scoured slopes in exposed areas. At treeline spotty, isolated areas of surface hoar growth exists (up to 3mm). This is most likely buried down 15-20 cm under the recent storm snow. Snowpack tests on a SE aspect around 1400m  showed CTH (resistant "pop") on an old facet layer 55 cm down, and a rutschblock score of 5. Generally, the mid-pack is gaining strength and possibly even bridging the persistent weakness below.Digging down deeper is the early November facet/crust deep persistent layer. This crust sits near the base of the snowpack down 80-130 cm. Test results on this layer earlier this week produced hard results ("drops"). I have no current observations to suggest the snow above or below this interface is gaining strength, or weakening.

Régions couvertes