Boletín de aludes

Purcells

Jan 9 – 10, 2014Avalanche Canada
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Archivado · caducó 13 years ago

Peligro de aludes

Sat
Sun
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Lo esencial

Complex avalanche conditions at the moment. The answer to this type of avalanche problem lies in conservative terrain selection. Visit the blog for thoughts on the recent pattern of accidents in the Purcells.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    2–5
    Wind slabs rest on top of two persistent weak layers in the upper meter of the snowpack. Triggering a wind slab could add a significant load to the snowpack and possibly step down to a deeper buried persistent weak layer.

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–6
    You would not build a house with a weak foundation and you can't trust a snowpack with this kind of structural weakness near the ground. You're most likely to trigger this layer on steep north through east facing slopes with a shallow snowpack.

Weather Forecast

A westerly flow dominates the next few days. A number of weather systems are lined up to bring varying amounts of precipitation and wind to the interior regions.Friday: Light snowfall, alpine temperatures -10, winds moderate to strong west and southwestSaturday: Moderate snowfall, alpine temperatures -8, winds strong to extreme west and southwest. Freezing levels possibly rising to 1200m in the morning.Sunday: Moderate snowfall, Alpine temperatures -8, moderate west winds. 

Avalanche Summary

There have been a few different close calls with large avalanches in the north of this region in the last three weeks. Check out the incident database for more details. There have been no recent reports of avalanche activity. However I would expect to see an increase in natural and rider/skier triggered avalanches as new snow amounts continue to accumulate and the wind speeds pick up over the next 2-3 days.

Confidence

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

Snowpack Summary

Up to 10 cm of new snow sits on a variety of snow surfaces ranging from stiff wind slab, a soft layer of facetted snow and/or surface hoar. These sit on top of old wind slabs and a couple of persistent weak layers that exist in the upper meter of the relatively thin snowpack. The mid December surface hoar is buried around 30-90 cm. The early December facet/crust combo is buried down 50-150 cm. Both interfaces give variable results with snowpack tests, but professional operators are treating them with caution.A bigger concern, especially in the Northern part of the region is a layer of weak sugary depth hoar crystals at the base of the snowpack that lie above a crust from early October. Several large avalanches in the last two weeks have been attributed to failures at this layer. Wide propagations on relatively gentle terrain have been noted, as well as a tendency for seemingly disconnected slopes to become connected by one large avalanche.

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