Bulletin d’avalanche

Purcells

Mar 7 – 8, 2013Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Sat
Sun
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible

Points saillants

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–5
    The soft slabs located below ridge tops and in open areas could become weaker especially on S facing slopes in the afternoon tomorrow with temperatures rising and if the sun is shining.
  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–6
    Persistent weak layers exist buried down 60-90 cm, comprising of surface hoar and a sun crust. A cornice fall could definitely trigger this layer. 

Confidence

Good

Weather Forecast

Thursday night and Friday: Precipitation associated with the upper low will ease off and give place to a light, cool and dry northerly flow. Trace amounts are expected on Friday with light North winds and temperatures around -6 C in the alpine. Overcast skies starting to clear in the afternoon and freezing levels rising to 1300 m.Saturday: High pressure brings dry conditions, mainly clear skies, light NW winds and freezing level rising up to 1400 m. in the afternoon. Sunday: A frontal system approaches from the North coast Saturday night weakening as it hits the interior but could leave some light precipitation amounts, slightly cooler temperatures and winds switching from the SW.

Avalanche Summary

An avalanche size 3 was naturally triggered in the past 48 h. on a steep SW facing slopes with a 100 cm deep fracture line. A few size 1 loose dry avalanches were reported in the new snow. SSL in alpine lee features are also reactive to explosives creating size 1, not propagating very far.

Snowpack Summary

Around 10 cm of new snow fell recently on the previous 40 cm of storm snow, older windslabs, a suncrust on S facing slopes and on a temperature crust below 1700  m. The new snow is sluffing easily with skier traffic and soft slabs could be triggered in alpine in wind effected areas on lee ridgetop features. Buried beneath (60-90 cm) exists a surface hoar and a sun crust layer, which continue to be lingering concerns. On solar aspects, the sun crust seems to be more reactive. Large looming cornices exist on ridgelines. Cornice fall could trigger a large slab avalanche on the slope below, especially when the sun comes out on Friday afternoon and Saturday. The sun and temperatures increasing tomorrow could weaken the snowpack especially on S facing slopes.

Régions couvertes