Bulletin d’avalanche

Purcells

Feb 14 – 15, 2016Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

Tue
Wed
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Triggering large persistent slab avalanches is still possible, especially in the north of the region. Remain diligent and continue to make conservative decisions.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    New wind slabs are expected to form on Sunday night in response to light amounts of new snow and wind. Watch for triggering in the lee of ridgecrests at treeline and in the alpine.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–5
    A weak mix of surface hoar and facets remain a concern, especially in the Dogtooth Range in the north of the region. A cautious approach is required in this area, as this layer may still surprise with nasty consequences.

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Sunday

Weather Forecast

SUNDAY NIGHT: 5-15cm of new snow / Strong southwest ridgetop winds / Freezing level at about 1400mMONDAY: Mix of sun and cloud / Moderate ridgetop winds / Freezing level at about 1200mTUESDAY: 5-15cm of new snow falling mostly in the early morning - easing by mid day / Strong southwest ridgetop winds / Freezing level at about 1400mWEDNESDAY: Mix of sun and cloud with isolated flurries / Light southwest ridgetop winds / Freezing level at about 1000m

Avalanche Summary

Observations have been extremely limited in the last few days, although a natural Size 1.5 avalanche was observed in the Golden Backcountry on Thursday that apparently ran on a reloaded bed surface in a wind loaded feature. The interface is suspected to be the early January weak layer. Natural persistent slab avalanche activity was also observed earlier in the week, with a report of two Size 2.5s also in the Dogtooth Range that also released on the surface hoar, facet and crust weakness as deep as a meter down. Light amounts of new snow and strong southwest winds are expected to form new wind slabs on Sunday night.

Snowpack Summary

On Sunday night, generally light amounts of new snow are expected to fall, and strong southwest winds are expected to form new wind slabs in lee features at treeline and in the alpine. The new snow will overlie wind slabs which formed throughout the weekend. About 10-30 cm below the surface, you'll likely find a melt freeze crust which exists in most places except for in high elevation shaded terrain. The early January surface hoar/ facet layer is typically down 70-90 cm. Recent avalanches have been failing on this interface in the north of the region (see avalanche discussion) and it continues to produce sudden planar results in snow pit tests. In general, the lower snowpack is well settled and strong, apart from some thin snowpack areas where basal facets exist.

Régions couvertes