Bulletin d’avalanche

Northwest Coastal

Mar 31 – Apr 1, 2013Avalanche Canada
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Archivé · expiré 14 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

Be alert to conditions that change with daytime warming. Danger ratings are likely to exceed posted levels if solar radiation is strong.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–6
    Large developed cornices loom over slopes. Forecast warming will increase the chances of failure with the potential to initiate large avalanches.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–6
    In some areas the March 9th layer can still be triggered and propagate across large distances creating surprisingly large avalanches.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Expect loose wet sluffs to fail on sun-exposed slopes.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Monday

Weather Forecast

Monday: High cloud / Moderate southwest winds / Freezing level at 2000mTuesday: Very light snowfall / Moderate west winds / Freezing level at 900mWednesday: Overcast skies / Moderate west winds / Freezing level at 1100m

Avalanche Summary

In recent days loose wet activity to size 2.5 has been observed in steeper sun-exposed terrain. On Friday a skier-triggered size 1 slab occurred on a solar aspect on March 9th surface hoar. This avalanche remotely triggered a 2nd slab (150m away) lower down in a similar terrain feature again on the March 9th layer.

Snowpack Summary

Surface snow has settled with the influence of warm temperatures and surface faceting continues on steep shaded slopes. Solar aspects in the alpine and all lower elevation terrain are now well into a daily melt-freeze cycle with sun-exposed slopes becoming very weak with daytime warming.Between 50-75cm below the surface is layer of surface hoar buried on March 9th which is variably reactive. In some areas it is stubborn and requires a significant trigger. In other areas the layer is still showing sudden planar or sudden collapse test results with the potential for large avalanches. Check out the Forecaster's Blog for related discussion.The mid and lower snowpack are generally well settled and strong. Having said that, basal facets may resurface as a concern with spring warming, particularly in the north of the region.Cornices are large and untrustworthy, especially when the sun is out.

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