Bulletin d’avalanche

Lizard-Flathead

Mar 5, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

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

A week of heavy snowfall and strong winds have left large storm slabs primed for human triggering. Avoid overhead hazards and stick to mellow terrain.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    Always look up and avoid exposure to overhead cornices.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3
    Storm slabs are primed for rider triggering, especially on leeward slopes and behind terrain features that are wind loaded.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2–4
    There have been two natural deep persistent slab releases in the past week. Both of these avalanches were on northeast aspects in the alpine, and released to size 3 or larger.

Confidence

High - Due to the number and quality of field observations

Weather Forecast

SUNDAY: Afternoon flurries with 5-10 cm of new snow, moderate southwest winds, alpine temperatures around -7 C.MONDAY: Cloudy with isolated flurries and trace accumulations, strong southwest winds, alpine temperatures around -10 C.TUESDAY: Cloudy with light flurries picking up in the afternoon, strong southwest winds, alpine temperatures around -10 C.

Avalanche Summary

A widespread natural avalanche cycle occurred on Friday night, with many size 2-3 cornice triggered avalanches on north and east aspects. Explosive avalanche control on Saturday produced size 2 storm slabs and ski cutting produced size 1-1.5 avalanches on wind-loaded features. Natural activity is expected to taper off, but storm slabs will remain primed for human triggering.

Snowpack Summary

Another 20 cm of snow fell on Friday, bringing the three day storm total to roughly 80 cm and the weekly total to almost 150 cm. Strong southwest winds have extensively redistributed the snow and formed large brittle cornices. The new snow is rapidly settling into a denser slab which sits over a variety of old surfaces including surface hoar, facets, stiff wind slabs, sun crusts, and a rain crust below 1900 m. Isolated basal weaknesses may still exist in shallow snowpack areas and appear to isolated to north-northeast aspects in the alpine.

Régions couvertes