Bulletin d’avalanche

Northwest Coastal

Jan 3 – 4, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Thu
Fri
Alpin
5 · Très fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort

Points saillants

A significant storm with heavy precipitation amounts and high freezing levels will result in a major avalanche cycle on Wednesday.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    3–7
    Extreme winds have set up touchy wind slabs that should be treated with the utmost respect.
  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely - Certain
    Taille
    3–8
    Large amounts of new snow with warming temperatures will create very touchy storm slab conditions.
  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    5–9
    Deeply buried persistent weak layers have the potential to be triggered from rapid loading by large amounts of snow or rain and/or cornice falls.

Confidence

Good - -1

Weather Forecast

An intense storm will bring heavy amounts of precipitation-expect around 25 mm Tuesday night and 30-40 mm on Wednesday. Freezing levels will rise to around 1500 m and then start to fall on Wednesday afternoon as a cold front passes over. The passage of the cold front will bring a further 10-20 mm precipitation for Thursday. Ridgetop winds will be extreme (up to 140 km/h) initially from the southwest, then becoming westerly. On Friday, another frontal system hits the coastal region bringing heavy precipitation near the coast and moderate amounts further inland.

Avalanche Summary

A few natural size 1-1.5 windslabs were observed in the last 24 hours near Stewart.A natural size 1.5 was observed below treeline near Terrace.

Snowpack Summary

The snow tap is still firmly on in this region, with almost continuous precipitation melding one layer of storm snow into the next. Sunday's storm added a further 45 cm of new snow to the ever increasing total; snow depths are currently at record levels for this time of year. Strong southwest to westerly winds have set up touchy windslabs on lee slopes. Large sensitive cornices exist. Expect further significant wind and storm slab development with the forecast weather.Previous weak layers in the midpack, including a surface hoar are gaining strength and becoming too deeply buried to be a concern except from very heavy loads (such as a cornice fall). The lower snowpack is generally well settled and strong.

Régions couvertes