Bulletin d’avalanche

Northwest Inland

Jan 23 – 24, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Tue
Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Conditions are improving, but the consequence of triggering a large persistent slab avalanche warrants a cautious approach to steep open terrain.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2
    Wind slabs are likely lingering at higher elevations. If triggered, they have the potential to 'step down' and trigger large deep persistent slab avalanches.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    Weak sugary snow exists at the bottom of the snowpack, creating the potential for full depth avalanches. Uncertainty revolves around what type of load is now required to trigger these deep persistent slabs.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

TUESDAY: Cloudy, light west winds, alpine temperatures around -8.WEDNESDAY: Cloudy, moderate southwest winds, alpine temperatures around -6.THURSDAY: Cloudy with isolated flurries, moderate to strong southwest winds, alpine temperatures around -4.

Avalanche Summary

Recent avalanche reports are limited to a size 1 skier triggered slab avalanche on a southeast aspect at 1350 m in the Howsons. Last week, a large deep persistent slab avalanche was reported in the Smithers area that released on weak snow near the ground. The avalanche occurred on a cross-loaded feature, and was likely triggered by a smaller wind slab stepping down to weak basal facets over a metre deep. Looking ahead, triggering wind slabs as well as lingering persistent slabs remains a possibility at higher elevations.

Snowpack Summary

5-20 cm of settled storm snow sits above a widespread rain crust up to about 1300 m. Recent winds have likely formed wind slabs on lee and cross loaded features. Several buried surface hoar layers have been reported 40-80 cm deep and have given variable results in snowpack tests. Many areas have hard slabs in the upper snowpack above weak sugary snow near the ground. Triggering a deep persistent slab above this sugary snow will remain a low probability high consequence scenario for some time.

Régions couvertes