Boletín de aludes

Purcells

Jan 6 – 7, 2012Avalanche Canada
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Archivado · caducó 15 years ago

Peligro de aludes

Sun
Mon
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely - Very Likely
    Tamaño
    2–5
    Windslabs have developed in the alpine and at treeline due to very strong southwest winds and warm temperatures during recent storms.

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    3–7
    This is the deeper slab problem that developed during the long dry spell in early december. This weakness has become more stubborn. Avalanches that release at this layer could be very large and destructive.

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely - Very Likely
    Tamaño
    2–5
    A slab has developed during recent stormy weather that is above a weak surface hoar layer that developed over a short period of clear weather at New Year's. This slab in itself may produce avalanches up to size 3.0

Confidence

Fair - Forecast snowfall amounts are uncertain on Sunday

Weather Forecast

Flurries during the day on Friday should accumulate a couple of new cm by Saturday morning. A weak ridge of high pressure building over the coast is forecast to develop strong winds from the west or northwest and warm temperatures in the Cariboo. Moderate precipitation is expected to begin by midnight and continue during the day on Sunday. The freezing level is expected to rise to about 1800 metres in the Cariboo and West Monashee by Sunday morning. It looks like most of the snow will fall in the North and West of the Interior ranges. Expect moderate to strong northwest winds on Sunday becoming strong from the west in the South Columbia and Purcells. Cooler air is expected to move in to the region from the northwest on Monday. Precipitation amounts are un-certain at this time. Chinook conditions are expected for the Rockies.

Avalanche Summary

Some explosive and skier controlled avalanches up to size 1.5. Observations have been limited due to poor visibility and travel conditions.

Snowpack Summary

The storm slab is about 50 cm in this region. In the alpine and at treeline this new snow is being blown onto lee slopes and terrain features adding to previous soft slabs and wind slabs. In sheltered locations this new snow buries the surface hoar that formed over the New Years. We'll date this the January 3 SH layer, the crystals reported to be up to 10mm. This may become a concern with increased load as it reaches it's threshold. Some locations in the region received some rain up to 2000m, but consistent rain to 1500m. This may have solved our lower elevation New Years surface hoar layer. Below the surface down 80-140cms lurks the mid-December surface hoar/ crust/ facet layer. This is a layer of concern. Test results on this are still variable in the moderate to hard ranges with sudden planar characteristics. It continues to be sensitive to large triggers like cornice fall and explosives. Between this layer and the bottom of the snowpack sits a well settled mid pack. At the bottom of the snowpack basal facets and depth hoar crystals live. These become a concern in thinner snowpack areas, and became reactive under the new load of the post-Christmas storms.

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