Bulletin d’avalanche

South Columbia

Apr 12 – 13, 2013Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

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

Snowfall amounts for Friday night are uncertain. Danger could spike to HIGH by Saturday if we get more than forecast.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    1–6
    A layer of surface hoar is buried about a metre down, mainly on high northerly aspects. A surface avalanche stepping down, cornice fall, or the weight of a person from a thin-spot trigger point could trigger it.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Snowfall on Friday night is expected to create new storm slabs, especially near ridge top and on slopes in the lee of the wind.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Saturday: Overnight snowfall tapering off to a cool and unsettled flow with light snow. Strong NW winds easing. Freezing level around 1200 m, dropping to 300 m overnight.Sunday: Cold and unstable weather, with light snow. Light N winds. Freezing level around 1000 m.Monday: Cold and unstable weather, with light snow. Light winds. Freezing level around 1700 m.

Avalanche Summary

A natural avalanche cycle to size 2.5 occurred on Wednesday in response to storm loading on all aspects in the alpine. Skiers triggered several size 1-2 wind slabs on N to NE aspects on Thursday. Many of these failed at the base of the recent storm snow on crust interfaces. Some observers mentioned solar-triggered avalanches as well.

Snowpack Summary

Snowfall on Friday night is expected to create new storm/wind slabs, especially near ridge top. This will add to existing storm slab and wind slab problems at alpine and treeline elevations. A surface hoar interface is buried within the upper metre or so of the snowpack, mainly on high-elevation northerly aspects. It may be slowly gaining some strength, but these slopes should still be treated with suspicion. On other slopes, recent storm snow overlies a crust, with a variable bond. At low elevations, previously rain-soaked snow is likely to now be refrozen and strong.

Régions couvertes