Bulletin d’avalanche

South Columbia

Feb 5 – 6, 2015Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

Sat
Sun
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort
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Points saillants

Strong winds, heavy snowfall, and rising temperatures have resulted in HIGH avalanche danger.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–6
    Buried persistent weak layers may be over-loaded by the forecast new storm snow resulting in human triggering, or storm slab avalanches in motion stepping down to the deeply buried weak layers.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    2–5
    Strong winds, heavy snowfalls, and rising freezing levels are expected to result in a widespread natural avalanche cycle within the storm snow or releasing on the late January buried crust.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Heavy snow and strong Southerly winds overnight, Friday morning, and Friday afternoon. Freezing levels climbing up to about 1800 metres in the North and east of the region, and closer to 2000 metres in the West and South of the region. Strong Southerly winds continuing on Saturday morning. Freezing levels dropping to 1400 metres on Saturday afternoon as the winds slow to moderate Southwest. Light Southerly winds combined with light precipitation and cooler temperatures on Sunday.

Avalanche Summary

Several natural avalanches up to size 2.0 were reported on Wednesday that released within the storm snow down 20-30 cm. Heavy loading from new snow and wind on Thursday is expected to have resulted in a storm slab cycle on the late January crust or on a change within the storm snow about 10-15 cm above the crust. Forecast strong winds and heavy snow are expected to increase avalanche size and avalanche frequency as the storm continues.

Snowpack Summary

Thin new slabs may not be bonding well within the storm snow. Pockets of wind transported snow at ridgetops may be easy to trigger where they are sitting on the crust that formed last week. The new storm slab is up to 40 cm thick and sits above a variety of old surfaces. The old surfaces include the crust that formed last week, a new layer of surface hoar that developed during the clear weather late last week, and in some places wind slabs that developed smooth hard surfaces. Deeper in the snowpack the mid-January surface hoar remains a concern. It can be found down 60-120 cm across the region, but in most places it is about one metre down. In some locations it has reportedly gained quite a bit of strength, but elsewhere it is still producing sudden collapse (popping) failures in snowpack tests. The mid-December surface hoar layer is now 80 to 140cm below the surface and has become unlikely to fail, the storm at the end of the week should be a good test to see if it will become active again.

Régions couvertes