Bulletin d’avalanche

Northwest Coastal

Dec 11 – 12, 2013Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Fri
Sat
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
3 · Marqué

Points saillants

Strong winds and heavy snowfall are expected to increase the Danger to HIGH by morning.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    2–5
    The warm new storm snow is expected to release naturally and may be very easy to trigger by skiers and sledders. As the storm slab builds expect large avalanches.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Overnight and Thursday: A strong pulse of Pacific moisture will continue to bring snow overnight, with 20-30 cm accumulating by morning. Snowfall should moderate during the day, another 10-15 cm is forecast. Strong Southwest winds overnight should gradually become moderate during the storm. Freezing level about 1000 metres.Friday: There should be a bit of a lull in the storm before the next pulse comes on-shore Friday evening. Expect flurries and light to moderate Westerly winds during the day, increasing to heavy snowfall and strong Southwest winds in the evening. Freezing level dropping below 700 metres.Saturday: 20-30 cms of new snow by Saturday morning with strong Southwest winds and rising freezing levels.

Avalanche Summary

The warm new storm snow is not expected to bond well to the shallow weak snowpack. Expect natural avalanche activity and easy triggering from skiers and sledders.

Snowpack Summary

New storm slab is 30 cm deep and growing. Strong Southwest winds are transporting snow and developing deep pockets that are sitting above recent weak surface layers. Rising temperatures during the storm are expected to develop a relatively warm storm slab above a cold layer of wind crusts, surface hoar and surface facets. Snow profile information from the Shames area on Monday before the storm on a South-Southwest aspect at 950 metres, showed a 70 cm base with loose snow in the top 20 cms above a stiff 4 cm crust that is sitting above a softer facet layer. There was another hard crust about 30 cms above the ground. The new storm is a great deal of change for this young and weak snowpack to handle.

Régions couvertes