Bulletin d’avalanche

Kootenay Boundary

Feb 27 – 28, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Check out the most recent forecasters blog which deals with decision making & the current hazard: http://bit.ly/sF10fT

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–7
    The Feb 08 surface hoar/facet/crust combination is now buried by up to a metre of new snow. As the snow above consolidates into a cohesive slab, avalanches triggered on this layer will become very large and destructive.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–3
    The 50 cm of storm snow that fell over the weekend has settled into a soft slab. The storm slab is sitting on top of the old windslabs and the Feb 08 persistent weak layer. Dry snow on north aspects is available for transport.

Confidence

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

Weather Forecast

Tue: Scattered high clouds. Alpine winds light W, switching to mod SW around lunch. 1500m Temp: H: -5, L: -10Wed: A low pressure system tracks S of the int'l border, but will deliver 5 -10cm to the KB throughout the day Wed. Alpine winds Strong W/SW. 1500m Temp: H: -4, L: -15

Avalanche Summary

Up to 50 cm of storm snow from the weekend has formed a soft slab that is reactive to human triggering. Numerous avalanches were triggered by humans & explosives on Sunday, many natural avalanches were reported too. These avalanches were as big as size 2.5 with crowns up to 100 cm in depth. Avalanches triggered in the upper 50 cm could easily step down to the surface hoar layer producing large unmanageable avalanches.

Snowpack Summary

Another 20 cm of dry light new snow on Saturday night and Sunday morning has combined with 30 cm from Saturday morning to add to the load above the highly reactive persistent weak layer (PWL), comprising large surface hoar in sheltered areas and a sun crust on solar aspects. This PWL is now buried by about 100 cm and resulting avalanches could easily be large enough to bury, injure or kill a person. Professionals throughout the region are treating this layer with extreme caution, since it is showing signs of remote triggering and the ability to propagate in low angled terrain. Strong winds last week created stiff windslabs that have been cracking and propagating long fractures. The new snow may make it difficult to identify these windslabs especially in openings at treeline and below. In the alpine there may be enough wind to create new windslabs that are softer and probably will not bond well to the old surface.

Régions couvertes