Bulletin d’avalanche

Northwest Inland

Jan 17 – 18, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

The storm continues to develop storm slabs above a weak shallow snowpack. Storm slab avalanches in motion may step down and result in large avalanches.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    New snow, warm temperatures, and strong winds have created a widespread storm slab problem, particularly on wind-loaded features. Storm slab avalanches in motion may step down and trigger deep persistent slab avalanches.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–3
    The potent mix of snow, rain, wind, and warm temperatures will keep the likelihood of natural and human triggered deep destructive avalanches elevated throughout the week.

Confidence

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

Weather Forecast

Storm continuing overnight with 5-10 cm of new snow and strong southwest winds. The overnight freezing level should be close to valley bottoms. Overcast with light snow (3-5cm), strong southwest winds, and freezing levels around 1000 metres on Wednesday. Overcast with light snow (2-3cm), moderate westerly winds and freezing levels dropping to valley bottoms on Thursday. Clearing and cooler on Friday with light winds.

Avalanche Summary

Expect developing storm slabs to be easy to trigger where they are sitting on a weak layer of surface hoar and/or a crust left behind after the cold and windy weather. Full depth avalanches continue to be a concern due to the weak facetted snowpack below the hard wind slabs left behind after strong winds from several directions. This deep persistent weak layer may take prolonged warm weather with consistent snowfall to settle and bond.

Snowpack Summary

10-15 cm of new snow now sits on a mix of old surfaces left behind after the recent cold and windy weather. Expect the new storm snow to bond poorly where it is sitting on a weak layer of buried surface hoar and/or a hard old wind polished surface. Most areas continue to have a shallow and weak snowpack that is about 100-140 cm at treeline. In general, the snowpack above treeline has been heavily wind effected; this has resulted in hard wind slabs above weak facettted crystals. The snowpack below treeline in sheltered areas may be unconsolidated with foot penetration close to the ground.

Régions couvertes