Bulletin d’avalanche

Northwest Inland

Jan 31 – Feb 1, 2015Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

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

As snow accumulates on Sunday, the Avalanche Danger will rise. Expect reactive new storm slabs to form.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–4
    In the mid snowpack there are a few crusts which may be reactive to the weight of a skier. Although less likely to trigger, these persistent weak layers may "wake-up" in response to continued storm loading.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3
    Snowfall and wind on Sunday will build new storms slabs. Watch for increased triggering in wind-exposed terrain.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–6
    Although less likely to trigger, recent avalanche activity suggests weak layers buried at the beginning of the winter should still be our radar, especially in the north of the region. Avalanches at this interface may reach their run-out zones.

Confidence

Fair - Due to the number of field observations

Weather Forecast

A series of pacific frontal systems will bring continued snowfall to the region.    Sunday: Up to 20cm of new snow / Moderate to strong southwest winds / Freezing level at valley bottom    Sunday night and Monday: Up to 10cm of snow / Moderate to strong southwest winds / Freezing level at valley bottom  Monday: Up to 10cm of snow / Moderate to strong southwest winds /  Freezing level at valley bottom

Avalanche Summary

Several storm slabs to size 2.5 were reported in the wake of Thursday night's storm. With more snow and wind on the way on Sunday, I'd expect continued storm slab activity. It's important to keep in mind, a surface avalanche in motion may be what it takes to trigger deeper, more destructive persistent slab avalanches.

Snowpack Summary

Prior to the weekend, moderate to heavy snowfall and strong southwest winds built deep storm slabs which are expected to be most reactive in wind-exposed terrain. Below treeline, these recent accumulations may overlie a hard, frozen crust. About 70cm below the surface, you'll likely find a rain crust which was buried on January 26. Limited observations suggest the overlying slab may have a reasonable bond at this interface.A rain crust and/or surface hoar layer buried mid-January may be found at variable depths (in some areas over 100cm below the surface). This layer is likely gaining strength, although I would keep it on my radar as it was the culprit in much of the recent destructive avalanche activity.Near the base of the snowpack is a crust-facet combination buried in November. This deep persistent weakness was also recently reactive, and may still be touchy in the far north of the region. Wherever you are, I'd be cautious of this deep and destructive layer. Possible triggers include thin spot triggering in high elevation terrain or a cornice fall.

Régions couvertes