Bulletin d’avalanche

Purcells

Mar 30 – 31, 2013Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Mon
Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Danger could INCREASE TO CONSIDERABLE with intense radiation on south and west aspects, especially at treeline and below. Be aware of how the warm weather is changing the snowpack. 

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    2–5
    Natural cornice falls are a concern during daytime warming. Cornices may also be triggered easily by traveling near them. Slopes with corniced entrances, or exposed to cornice falls should be avoided with these conditions.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–6
    Small solar triggered slides, cornice fall, or thin-spot triggering may overload a persistent weakness buried near 100 cm deep. This could lead to surprisingly large avalanches. Wind slabs linger on lee slopes and cross-loaded terrain features.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–5
    Expect to see wet loose snow avalanches out of steep rocky sun-exposed slopes. Natural avalanche activity. snowballing, moist and wet snow surfaces are all initial indications of the upper snowpack deteriorating.

Avalanche Summary

Numerous natural loose wet avalanches up to size 1.5 and one natural cornice fall size 2.5, not pulling a slab on the slope below.

Confidence

Good

Weather Forecast

A dominating high pressure system with sunny skies, rising freezing levels and light winds continues through to Monday. The pattern will start to deteriorate by Tuesday, showing increased cloud and grey skies with no precipitation. Sunday: Few to scattered high cloud. Alpine temperatures 4.0 and freezing levels 2600 m. Ridgetop winds light from the NW.Monday: Scattered clouds. Alpine temperatures 5.0 and freezing levels rising to 2600 m. Ridgetop winds blowing light from the NW.Tuesday: Cloudy. Alpine temperatures -1.0 and freezing levels falling to 2300 m. Ridgetop winds blowing light from the SW.

Snowpack Summary

Surface faceting and surface hoar growth (up to 20 mm) has been prevalent on most aspects and elevations, while the surface snow on sun-exposed slopes and at lower elevations has been subject to daily melt-freeze cycles.Cornices are large and weak. Pockets of wind slab can be found on lee slopes and possible to trigger under your skies or sled. A layer of buried surface hoar sitting on a crust down around 70-120cm, and has been producing variable results in snowpack tests. This persistent weakness remains a concern because of the potential for very large avalanches particularly with heavy triggers such as cornice falls. Old deep persistent weaknesses, including basal depth hoar, are a concern in shallow snowpack areas.

Régions couvertes