Bulletin d’avalanche

Kootenay Boundary

Mar 23 – 24, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Sun
Mon
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

This is the first big warm-up after some significant snowfall. A warming-related avalanche cycle is expected.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–6
    Cornices are very large and may fail with daytime warming, especially with sunny breaks. There is potential for triggering deep slabs on underlying slopes.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Recent new snow has set up storm slabs in many areas. Warm temperatures are likely to make this reactive.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3–8
    The deep nature of the mid-February surface hoar layer makes potential avalanches triggered on this layer large and destructive. Avoid thin snowpack areas where triggering is more likely.

Confidence

Poor - Timing or intensity of solar radiation is uncertain

Weather Forecast

Saturday will stay mostly dry, with sunshine and cloud. Winds should remain light. Freezing level should go to around 1800 m during the day. Sunday looks bright, sunny and warm, with freezing levels going up to around 2500 m. Very little overnight cooling is expected Sunday night as clouds move in overnight. Monday will stay warm, with freezing level around 2400 m and some good periods of sunshine.

Avalanche Summary

Several relatively small avalanches occurred in the storm snow on Thursday and into Friday. A fatal avalanche incident occurred in this region on Wednesday. We will post more details when they become available. On Monday and Tuesday avalanche activity was isolated to the recent storm snow. On Sunday a large avalanche occurred in the Lumberton snowmobile area in the East Kootenays: a snowmobiler accidentally triggered a very large (Size 3+) avalanche that resulted in a close call.

Snowpack Summary

10-20 cm new snow on Wednesday night followed a previous 20-30cm of new snow on Tuesday. This new snow has built storm slabs in many places and wind slabs in exposed leeward terrain. A sun crust that recently formed on southern aspects to around 1700 m and a spotty 2-6mm surface hoar on north and east aspects are now buried around 60-100cm. Below that, the more significant early February surface hoar is down 100-180cm. Avalanche activity has become more sporadic on this layer, but ongoing large events indicate it still has the ability to fail, despite how deeply it is buried. A melt-freeze crust, down 20-30cm, below 1800m provides some bridging to the layers below. Below the early February surface hoar layer, the snowpack is strong in most places. Cornices are very large and would act as a significant trigger for all the layers mentioned above if they drop.

Régions couvertes