Bulletin d’avalanche

South Rockies

Dec 12 – 13, 2015Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Touchy avalanche conditions exist from all the recent snowfall. Use a cautious approach in the mountains this weekend.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    New snow will likely be sensitive to human triggers, and particularly deep and weak on the leeward side of ridge crests and in wind-loaded chutes.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–5
    The weakness buried early-December is becoming more stubborn to trigger, but lingering pockets of buried surface hoar and facets may maintain touchy conditions on sheltered slopes, especially in the 1700-2100m elevation range.

Confidence

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

Weather Forecast

The last of the Pacific storm pulses is expected to hit the region Saturday overnight. Around 10cm of snowfall is expected with freezing levels around 1200m. Light scattered snowfall may continue through the day on Sunday. Alpine winds are expected be strong from the SW in the morning but will ease in the afternoon. Monday is expected to be dry with a mix of sun and cloud. Freezing levels are forecast to drop to near valley bottom and alpine winds should be light from the NW. Tuesday looks to be similar with mainly dry condition and a mix of sun and cloud.

Avalanche Summary

Reports from Thursday include a remotely triggered Size 1.5 slab avalanche from a snowmobiler on a sheltered north facing slope below treeline that ran on surface hoar buried early-December. On Friday, ski cutting produced size 1 soft slabs in immediate lee features (generally north through east aspects).

Snowpack Summary

Continued snowfall brings total treeline snowpack depths to over 1m, with even more in the alpine, but it diminishes quickly below around 1700m. Recent rain created a near surface crust as high as 1800m (or higher in the southern part of the region). Above that elevation, storm and wind slabs are bonding poorly to the old snow surface buried early December, which is probably a crust and/or a combination of facets and buried surface hoar now down around 40-60cm in sheltered treeline areas. The buried surface hoar may be well preserved in sheltered areas, creating particularly touchy slabs with the potential for remote triggering, extensive releases and prolonged sensitivity to triggering. Below that a thick weak layer of facets may be lurking around the thick mid-November crust.

Régions couvertes