Bulletin d’avalanche

Northwest Inland

Feb 24 – 25, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–6
    Increasing winds and new snow through the forecast period will form wind slabs on lee slopes and terrain features. Expect to see more widespread loading due to changing winds.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–5
    Forecast snow and wind will increase the soft slab load on the variable buried weak layers. I suspect this to be a concern as these layers reach their "Tipping Point" where natural and human triggered avalanche activity will increase.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Saturday: Expect an unsettled day, with winds turning northeasterly and some isolated flurries giving another 10cm. Temperatures could climb to -10. Sunday & Monday: Mostly clear skies with light northerly winds and cold temperatures. Clouds will begin to build late in the day on Monday as the next system arrives.

Avalanche Summary

Natural avalanches up to size 3.0 and ridder triggered up to 1.5 have been observed.

Snowpack Summary

Up to 30cm of new snow has fallen over the past week, and sits on a variety of old surfaces. These surfaces include: melt-freeze crusts that exist on all aspects at lower elevations and on south-facing slopes higher up and well-settled powder on shaded aspects in the alpine. Weak surface hoar crystals (size 3-4mm) are sandwiched between the old surfaces and the newer snow and have recently shown easy compression test results. The distribution of the surface hoar seems to be up to treeline on all aspects and on sheltered features in the alpine. This upper snow pack structure will be the big thing to watch as the overlying slab develops. I expect to see increasing reactivity in the surface hoar interface. The mid and lower snowpack are generally well settled and strong.There is a Special Public Avalanche Warning in place for most of the province, including the Northwest Inland area.

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