Bulletin d’avalanche

South Coast

Apr 16 – 17, 2015Avalanche Canada
Voir sur la carte
Archivé · expiré 11 years ago

Danger d’avalanche

Sat
Sun
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
Ouvrir la carte complète

Points saillants

Solar radiation and rising temperatures will destabilize the snowpack and avalanche hazard can rise quickly. Watch overhead hazards like cornice fall. Loose wet sluffing and solar triggered slab avalanches.

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
    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

Fair - Due to the number of field observations

Weather Forecast

A pacific front hits the North and Central coast Thursday evening and then slides south towards the South Coast. Confidence is poor with determining how far this storm will track south. Lingering cloud, sunshine and periods of convective snowfall may occur on Friday. Ridgetop winds will be light from the SW and freezing levels near 2000 m.  Friday evening a warm ridge builds over the province bringing sunny and dry conditions into early next week. Saturday and Sunday freezing levels will be steady near 2700 m with intense solar radiation and ridgetop winds remaining light.

Avalanche Summary

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. This will likely initiate a natural avalanche cycle. Watch overhead hazards like cornice failures and solar induces loose wet, and slab avalanches.

Snowpack Summary

Anywhere from 20 to 50 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