Bulletin d’avalanche

Purcells

Jan 4, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Sat
Sun
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort
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Points saillants

The region will continue to see substantial snowfall amounts into Friday, which is rapidly loading buried weak layers. Travel in avalanche terrain is not recommended.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1.5–3
    Expect to find reactive storm slabs at all elevations due to recent storm snow, strong winds, and mild air temperatures. Triggered slabs could step down to deeper weak layers.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–3.5
    The likelihood of triggering deeply buried weak layers is increasing with the recent snowfall and warm air temperature. Should an avalanche occur, it could run full-path and well into the valleys.

Confidence

High -

Weather Forecast

THURSDAY NIGHT: Cloudy with snowfall, accumulation 10 to 20 cm, moderate to strong southwest winds, alpine temperature -4 C, freezing level 1400 m.FRIDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwest winds, alpine temperature -3 C, freezing level 1500 m.SATURDAY: Mix of sun and cloud, light southwest winds, alpine temperature -4 C, freezing level 1000 m.SUNDAY: Cloudy with light snowfall, accumulation 5 to 10 cm, light to moderate southwest winds, alpine temperature -3 C, freezing level 1000 m.

Avalanche Summary

Storm slabs were reactive to skier traffic and explosives on Thursday, producing large (size 2) avalanches with depths around 20 to 40 cm.  It is possible that a natural avalanche cycle will occur as the storm continues Thursday night and into Friday. Avalanches could run fast and far, well into runout zones.

Snowpack Summary

A strong storm is dumping snow in the region Thursday into Friday. Around 20 to 40 cm of snow has fallen over most of the region up to Thursday evening (almost 70 cm in the far north!), and another 20 to 30 cm is expected Thursday night into Friday. All this snow has likely formed touchy storm slabs. The snow is falling with strong westerly winds, so expect deeper deposits in lee terrain features near ridges.All this snow is loading a weak layer that formed during the dry spell in early December. It is around 80 to 120 cm deep. The layer is composed of weak and sugary faceted snow, feathery surface hoar crystals, and on south aspects also a sun crust. Another similar weak layer is buried around 120 to 150 cm deep. The base of the snowpack has weak faceted layers at alpine and treeline elevations. These basal weak layers have been producing large avalanches as recently as December 31. Human triggering any of these layers is most likely on slopes that didn't previously avalanche and on slopes that have variable snowpack depth, such as rocky alpine features.

Régions couvertes