Bulletin d’avalanche

Northwest Coastal

Dec 23 – 24, 2012Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Tue
Wed
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    New wind slabs have formed in response to down-valley winds. These could be triggered by the weight of a person or snowmobile.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    1–7
    A deeply buried weakness may be triggered from thin, rocky snowpack areas or with a large trigger.

Confidence

Fair - Due to variable weather conditions

Weather Forecast

Monday: Light S winds, with moderate to strong NE outflow winds in places. Alpine temperatures around -11 with an inversion (colder temperatures in the valley floor).  No precipitation.Tuesday: Light winds. Alpine temperature around -9 with an inversion. No precipitation.Wednesday: Light S winds. Alpine temperature around -10. No precipitation.

Avalanche Summary

On Saturday, several natural size 1-2 loose dry and thin slab avalanches failed in steep isolated terrain features wind-loaded by outflow (down-valley) winds. Explosives triggered size 2-3 slabs which failed near the ground in facets. Near Bear Pass, natural ice fall triggered size 2.5 and 3 loose snow avalanches, entraining old storm snow.

Snowpack Summary

Wind slabs and cornices have developed on a fairly widespread basis and may be found in unusual locations lee to NE and E outflow winds. Surface faceting is likely to continue while the weather remains cold. A layer of surface hoar buried in the upper metre of the pack has been observed in the Shames backcountry. The midpack is generally well settled. Near the base of the snowpack, a crust/facet layer continues to give hard, sudden results in snowpack tests. This weakness is unlikely to be triggered by a single person, but it remains possible with a very heavy load (e.g. cornice fall) or from a thin-spot trigger point.

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