Bulletin d’avalanche

Purcells

Dec 18 – 19, 2015Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

Sun
Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

The new snow may be hiding pockets of old wind slab on south aspects with new soft slabs developing on north facing lee features through the day.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    Variable winds and an abundance of low density snow available for transport will continue to produce wind slabs in lee features. Look for shooting cracks as a sign you entering wind a wind loaded feature.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–4
    A layer of buried surface hoar can be found between 1400m and 1800m. Watch out for signs of instability like wumphing to guide you through this elevation band.

Avalanche Summary

Avalanche professionals in the field are reporting small slab avalanches in the immediate lee of wind loaded features.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

SATURDAY: no significant precipitation is expected, moderate westerly winds, accompanied by a warming trend with a high of -5C at treeline. SUNDAY: light snow with accumulations of up to 5cm by the end of the day, moderate southerly winds, -5C at treeline. MONDAY: isolated flurries, light southerly winds, temperatures are forecast to fall to -10C at treeline through the day.

Snowpack Summary

Variable winds have produced localized wind effect in the new snow at ridgeline. About 15 to 40cm of snow sits above a crust that extends up to 1800m. A more extensive persistent week layer is buried between 30 and 80cm down. The form of this layer varies depending on aspect and elevation: it can be found as a crust on south facing slopes in the alpine, or as large grained surface hoar and facets below tree-line. The surface hoar is most widespread in an elevation band between 1400m and 1800m although it may extend higher south of Invermere. Snow pit tests suggest that human triggering of this interface is still possible, although unlikely. Below this the snowpack is thought to be mainly well settled.

Régions couvertes