Bulletin d’avalanche

Kootenay Boundary

Mar 16 – 17, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Sat
Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

We're still in a period of dangerous avalanche conditions. A brief break in the weather on Friday won't be enough for the snowpack to stabilize.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–4
    The snowpack has undergone rapid warming and destabilization in the past couple days, and buried persistent weak layers may still be reactive. Smaller avalanches may step down to deeper layers or the sun may trigger a deep release.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3
    In the high alpine, storm slabs are expected to remain touchy on Friday, especially in wind loaded terrain. Extra caution is also needed around cornices and sun exposed slopes.

Avalanche Summary

Reports from Wednesday confirmed an ongoing natural cycle of wet slab and loose wet avalanches up to size 3. Much of the activity was between 2000 and 2400 m on a variety of aspects. One large avalanche was triggered by a cornice fall on a north aspect. Explosive control also produced numerous size 2-3 wet avalanches.On Friday, storm slabs will remain reactive at higher elevations, particularly if the sun comes out in the morning. Large persistent slab avalanches also remain a serious concern until the snowpack has time to recover from the recent rain and warming.

Confidence

Moderate -

Weather Forecast

FRIDAY: Increasing clouds before the next storm arrives Friday evening, light southwest winds increasing throughout the day, freezing level up to 1500 m with alpine temperatures around -3 C.SATURDAY: Storm starts on Friday night and delivers 25-40 cm, strong southwest winds, freezing level up to 2000 m.SUNDAY: Clearing skies following the storm as alpine temperatures drop to around -8 C, light to moderate west winds.

Snowpack Summary

After several days of heavy rain, dropping freezing levels have left a thick rain crust up to about 2200 m. At higher elevations, large amounts of storm snow likely exist. At lower elevations, the rain has soaked the upper snowpack up to 50 cm deep. Several deeper weak layers were tested during the storm including the late-February facet / surface hoar interface (70-120 cm deep), the mid-February crust (90-130 cm deep), and basal facets in shallow snowpack areas. These layers may remain reactive a bit longer as the snowpack gradually cools off.

Régions couvertes