Bulletin d’avalanche

Northwest Inland

Mar 2, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Strong to Extreme winds accompanied by 5-10 cm will likely build reactive wind slabs. Deeper slabs may exist on leeward slopes.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–2
    Strong to extreme SW winds and new snow will build fresh wind slabs on leeward slopes and behind terrain features. Loose dry avalanches may be easily triggered below treeline or in areas sheltered from the wind.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2–4
    A lingering weakness at the bottom of the snowpack may remain sensitive to human triggering, especially in shallow snowpack areas. Smaller avalanches in motion also have the potential to step down and trigger deep persistent slabs.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Wednesday night-Thursday: snow amounts 5-10 cm with light winds gusting extreme from the SW. Alpine temperatures near -3 and freezing levels 1000 m. Friday: Periods of snow 2-7 cm. Ridgetop winds light gusting to 65 km/hr from the SW. Alpine high of -8 and freezing levels falling to 500 m. Saturday: Mostly cloudy with sunny periods. Ridgetop winds generally light. Alpine temperatures high of -10 and freezing levels at valley bottom.

Avalanche Summary

On Tuesday, no new avalanche activity was reported. With forecast snow and strong winds, reactive wind slabs are likely over the next several days.

Snowpack Summary

New snow 5- 15 cm accompanied by strong- extreme SW winds is burying a plethora of old snow surfaces including isolated wind slabs and wind press, sun crusts, and surface hoar. The new snow may have a poor bond to these interfaces. At treeline elevations the average snowpack depths are 150-190 cm and a well consolidated mid-pack of approximately up to 100 cm sits above weak basal facets (sugary snow) near the ground. Recent snowpack testing has shown sudden results down 100 cm within the facetted snow. Although possibly a low probability for triggering the persistent slab exists, the consequence would be high as it has the potential to produce very large destructive avalanches especially in shallower snowpack areas.

Régions couvertes