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Backcountry Advisory

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The past week has been, well... have you ever seen the movie Ground Hog Day?

All the same, if you think we have it bad just consider how grim the snow scene is anywhere east of Duffey Lake. Most regions between here and the Alberta foothills offer little more than a blend of gravel, facets, alder and surface hoar, with the odd slab thrown in to keep it scary. Despite province-wide drought conditions the persistent weaknesses continue to produce avalanche accidents including fatalities, mostly in the Columbia River Ranges.

Our situation is not quite so dire but still holds potential. Our November facet layer down near the ground is currently just hibernating, awaiting the right load to bring it to life again. The recent cold and clear conditions have further weakened our snowpack, primarily in the surface layer and in the usual shallow and rocky snowpack areas.

Large surface hoar crystals grew under the cold and clear night time skies and have most recently been buried under a 3 cm layer of new snow. These crystals resemble and have all the structural strength of a layer of taco chips when buried under a slab of snow.

The cold air conditions also created a strong temperature gradient in shallow snowpack areas and in the top layers everywhere else, creating faceted snow grains. Both the surface hoar and facets are called persistent weaknesses due to the profound tendency to remain weak for very long periods of time (the November facet layer is a case in point).

It’s beginning to seem like quite a stretch but some day we may get a real storm cycle and when we do it would be wise to remember the presence of these weaknesses and plan for more than the usual new snow instabilities.

Another backcountry hazard worth noting this season is the unusually weak snow bridging over the crevasses on our glaciers. Shallow snowpack and weak snow strength has provided the recipe for a few very nasty crevasse falls lately, resulting in some serious injuries and some near death experiences. Any further new snow will only add to the problem by further hiding the holes that have been opening up. It may be time to pull out the glacier travel gear if you are serious about travelling in glaciated terrain this year.

A series of weak frontal systems are forecast to affect our area into the weekend with cool temperatures and at least some new snow accumulation. Presently strong southerly winds accompanying the first wave are hopefully destroying most of the surface hoar. However certain lee pockets will likely be protected in the alpine and the surface hoar should survive just fine below treeline.

The longer range forecast is for (brace yourself) a return to high preasure and blue skies, but they have been wrong before...

For futher backcountry advisories contact the Canadian Avalanche Centre Public Buletin (1-800-667-1105 or www.avalanche.ca) or the Whistler/Blackcomb Backcountry Advisory updated daily (938-7676)

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