Bulletin d’avalanche

South Columbia

Feb 14 – 15, 2013Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

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

New wind slabs have been reported to be deeper than expected and easy to trigger. New storm slabs are also reported to be easy to trigger and running fast on a combination of crusts and buried surface hoar.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–5
    Strong Northwest winds have created thick new windslabs that may be triggered by light additional loads. Wind slab fractures may propagate quickly due to the presence of buried surface hoar and/or sun crusts.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–6
    There are older layers of buried surface hoar and crusts that are unlikely to be triggered by the weight of a skier or sledder, but may be triggered by large additional loads like cornice fall or wind/storm slab avalanches in motion.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–5
    A new soft slab is developing above the recent buried crusts, wind slabs, and weak surface hoar crystals. This new slab may be very easy to trigger on steep rolls and unsupported terrain features.

Confidence

Fair - Due to variable snowpack conditions for the entire period

Weather Forecast

Overnight and Friday: There is a chance of a couple of cms overnight as a weak band of moist air moves across the region. Strong Northwesterly winds overnight are expected to diminish to moderate during the day. There may be a period of broken skies or mostly clear skies in the afternoon. Alpine temperatures are expected to be about -3.0 and the freezing level should be about 1300 metres.Saturday: The moist air on the South side of the trough is expected to bring 10-15 cms of snow to the region as it passes through from the Northwest. Upslope areas in the West Monashee may see enhanced snow fall amounts during periods of convective flurries as the trailing cold front passes.Sunday: The next weak ridge of high pressure is expected to develop over the interior, bringing cooler temperatures and drier conditions.

Avalanche Summary

Explosives control resulted in avalanches up to size 2.5 in the North Selkirks. Natural avalanches occurred in the highway corridor up to size 3.0, and in remote areas up to size 2.5. Skiers controlled avalanches up to size 1.5 and some were surprised by accidental releases up to size 1.0

Snowpack Summary

There is a lot of variability in the depth of the new snow slab and the new wind slabs. Areas that received 30-40 cms of new snow have developed thick new wind slabs at higher elevations that may be triggered by light additional loads. The storm slab in these areas has been reported to be reactive to skiers, as it slides easily on a layer of surface hoar that developed just previous to the latest storm. In some areas there is a sun crust that developed during the sunny weather last weekend that is a smooth and fast sliding layer for the new storm slab. Deeper weak layers continue to show planar results in snow profile tests down about 70 cms and also at about 100 cms. These deeper layers are less likely to be triggered by skiers, but cornice falls or other large triggers may step down and result in large avalanches.

Régions couvertes