Bulletin d’avalanche

Kootenay Boundary

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

Avalanche danger is high due to loading from new snow or rain, and wind.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–5
    The significant load and rain deteriorating the late January crust could lead to avalanches stepping down to the deeper weak layers.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–4
    Snow or rain continues to accumulate making avalanches more likely to slide naturally. Windslabs developing on northeast aspects at higher elevation and wet slabs/loose avalanches problems at all elevations are incorporated into this problem.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

The second pulse of warm and mild weather associated with the low pressure system off the coast is expected to spread heavy precipitation over the region tonight (20-30 mm) and through Friday (20-30 mm).  Freezing levels could reach up to 2500m during the night and lower back down to 1800m tomorrow. A third wave of moisture with similar characteristics as the one before will be drifting inland on Friday night bringing another 20-25 mm of precip during the night and through Saturday. Freezing levels are expected to be around 1800m. Sunday is still looking warm but somewhat dryer. Winds are forecast to be moderate to strong from the southwest for the whole period.

Avalanche Summary

Multiple natural and skier triggered avalanches up to size 2.5 were reported within the storm snow some of which had impressive propagation potential.

Snowpack Summary

Around 20-25 mm of heavy snow, or rain below 1500m, has accumulated over 10-20 cm which is sitting on a widespread weak layer made of a hard crust topped by large surface hoar (referred to as the late January crust/surface hoar layer further down).  Significantly more load  is expected to add on to the snowpack through the night and tomorrow (total 40-60 mm as rain up to around 2200m) driving the avalanche danger to rise and making travelling conditions very dangerous in the backcountry. The rain is expected to weaken the late January crust/surface hoar layer, therefore increasing the likelihood of avalanches stepping down to deeper weak layers. The mid-January weak layer of buried surface hoar is now down 35-75 cm. The mid-December crust/facet/surface hoar combo found down 60 - 110 cm and could come out of its dormant stage making for some very large avalanche potential .

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