Bulletin d’avalanche

South Coast

Apr 19 – 20, 2015Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

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

This is the last avalanche bulletin with danger ratings for this region this season.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    3–5
    Recent cornice growth has been observed and large cornices are expected to become weak with solar radiation and daytime warming. Cornices could trigger large slab avalanches.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–5
    Two persistent weak layers sit in the upper snowpack. One is down 20-50 cm and has been recently reactive naturally and to human triggers. The second one sits 50-150 cm down and may re-awaken with warming, cornice fall and step down avalanches.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–3
    Solar radiation and rising freezing levels will deteriorate the snowpack. Travel on sunny slopes early, and watch for obvious signs of instabilities like avalanches, moist surface snow and snowballing.

Confidence

Poor - Due to the number of field observations

Weather Forecast

Mostly clear overnight with light winds and freezing levels remaining above 2400 metres. Mostly sunny with light winds and freezing levels rising up to about 3000 metres on Monday. Alpine temperatures are expected to be around +10 celcius. The ridge of high pressure is expected to break down sometime Tuesday allowing a weak system to move onto the south coast.

Avalanche Summary

No new observations reported. On Wednesday, natural cornice fall was reported, pulling thin slabs up to size 1 from the slopes below. Strong solar radiation and warming expected through the forecast period will likely initiate a natural avalanche cycle. Watch overhead hazards like cornice failures and solar induced loose wet, and slab avalanches.

Snowpack Summary

Anywhere from 20 to 40 cm of recent storm snow sits on a persistent weak layer comprising of crusts, surface hoar and facets which were buried April 10th. Moderate to strong south west winds are redistributing the storm snow into wind slabs on leeward slopes and terrain features. The mid-March persistent weak layer of facets on a crust is now approximately 50-100 cm down and continues to sit dormant. There is a low probability of triggering this layer, however; if it is triggered the consequence would be high. Large looming cornices may become weak with solar radiation and daytime warming. If a cornice fails it could trigger a large avalanche from the slope below.

Régions couvertes