Bulletin d’avalanche

Northwest Coastal

Dec 12 – 13, 2011Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–4
    Expect new wind slabs on north through east aspects. Loading may occur lower on the slopes due to forecast high winds in some parts of the region.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–3
    Storm slabs will continue to form with forecast snow. Pay attention to the snowfall amounts in your local area, they may vary through the region. More snow = thicker slabs. They can run far, fast and be destructive.

Confidence

Fair - Forecast snowfall amounts are uncertain on Tuesday

Weather Forecast

Tuesday: We could wake up to 10-15cm of new snow. Through the day we may see up to another 10cm. Ridgetop winds will be strong from the south west. Treeline temperatures near -5, with freezing levels at valley bottom. Wednesday/ Thursday: A ridge will rebuild over the area bringing a mix of sun and cloud, with more snow expected later in the week.

Avalanche Summary

One natural size 2.5 was reported on a steep NE aspect at 1200m failing to ground. No additional information on this avalanche. Expect avalanche activity with current conditions and forecast weather.

Snowpack Summary

New snow and wind over the next 32 hrs will add an additional load to the current snowpack. The upper snowpack consists of a variety of snow surfaces. The region did receive up to 20cm of snow early in weekend which produced sluffing in steeper terrain features. It also buried a variety of snow surfaces including surface hoar, a melt freeze crust, and facets (sugary snow). Most operations in the region have reported large surface hoar (feathery type snow crystal) that is sitting on a thick melt-freeze crust. This crust is up to 20cm in thickness and extends up to alpine elevations in the south, and around 1000m in the north. A strong temperature gradient in the top 30cm was reported to be faceting snow below the surface crust. The mid and lower snowpack are generally well settled and strong. My main concerns are new wind slab formation on lee slopes. With the strong ridge top winds you can expect some wind slabs lower on slopes, or found in unsuspecting places. Storm slabs may also be an issue if they reach threshold over the weak buried snow surfaces. They can run fast, and far.

Régions couvertes