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BACKCOUNTRY ADVISORY

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As of Wednesday, Jan. 31

The past week has seen our weather pattern switch back to something close to normal, thank god. Two frontal waves blessed us with 30 cm of much needed new snow and freezing levels down to the valley. Strong southerly winds during the storms loaded our lee alpine and treeline terrain with the usual soft slabs we used to be so familiar with.

Stability test results from local observers are showing a reasonably strong bond where the new snow meets the old surface. Sheltered areas below treeline may have a surface hoar weakness at this interface, which should be carefully watched for. Weaker shears can be found within the new snow layers, generally 10 to 30 cm down where a softer layer exists under the stiffer surface slab. Unless you are riding the fat boards you should notice this condition immediately as the skinnier planks really want to dive deep.

So far no activity has been noted involving the now infamous November facet layer. In the areas surrounding Whistler this layer has been gradually strengthening and appears to be fading from our radar screens a bit. Certain terrain features should still be treated cautiously in regard to this deep weakness, such as shallow snowpack and steep rocky areas where the facets are still loose and weak. Even fat snowpack areas may still produce on this layer if loaded significantly (falling cornice, extreme precipitation…). The deep facet weakness is much more significant in the ranges to the east, such as Duffey Lake or Bralorne where the snowpack is much more shallow. Any significant loading or warming out this way will likely bring this layer to life in dramatic fashion.

The weather forecast calls for significant precipitation, high winds and hopefully short periods of rising freezing levels for Thursday and Sunday. Currently the avalanche hazard rating is MODERATE but the rating is forecast to trend to HIGH with the above scenario. The red flags are up and backcountry travellers should pay close attention to observations out in the field. Talk should centre not just on where is the best "Pow" but indicators of snow stability as well. The more careful observation and sharing of information the better. Two good places to start are the Whistler-Blackcomb daily backcountry advisory at 938-7676 and the Canadian Avalanche Centre Public Bulletin at 1-800-667-1105 or www.avalanche.ca

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