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Backcountry Advisory

As of Wednesday, January 16, 2007

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Alpine: MODERATE

Treeline: LOW

Below Treeline: LOW

The Avalanche Danger is expected to increase at all elevations on Friday and Saturday .

Travel Advisory : 14 cm of light density snow fell on Monday night and Tuesday morning. The snowfall was accompanied by moderate winds at the mountaintops from the Southerly direction. The new snow layers are resting on a variety of old surface features ranging from hard wind-affected surfaces, to stiff windslab, to settled storm snow.

Avalanche Activity: Widespread skier-triggered soft slabs and loose sluffs were observed on Tuesday morning on any steep slopes in the Alpine. Although this type of activity is generally harmless, given a long enough slope enough snow could be entrained to get a skier into big trouble in any exposed terrain. Cornices have grown substantially with the strong winds during the past week and they are very fragile. Natural cornice fall early this week has left debris chunks the size of vehicles in some north facing bowls in the near country. Explosive testing on Sunday and Monday has also produced large cornice releases with truck-sized chunks hitting the slopes below. These cornice chunks have been a good test for the underlying slopes and we have seen little in the way of slab activity.

Snowpack : We received close to 100 cm of snow during the past week. The snow arrived in waves associated with warming temperatures and extreme winds. Surface hoar has been forming overnight since Thursday. It is particularly significant at treeline and below treeline. Below the most recent storm snow layers there is a layer of surface hoar that was most evident at and below treeline elevations. This layer could prove to be a future problem once loaded by additional snowfall. Buried faceted crystals caused by a strong temperature gradient in the upper snowpack could also show up with future loading. Thrown into this potpourri is a new layer of surface hoar that formed last night.

Weather : Mixed conditions are expected to prevail for the next few days as a cool Northwesterly flow enters our region bringing a mix of sun and cloud and periods of light snowfall. A more consolidated Westerly flow is expected to arrive on Friday and Saturday, with the main energy currently appearing to be to the north of our region. There is little in the way of consensus in the various long-range models for next week, so anything that you read should be ingested with a grain of salt.

Conditions may vary and can change rapidly. Check for the most current conditions before heading out into the backcountry. Daily updates for the areas adjacent to Whistler/Blackcomb are available at 604-938-7676, or at surf to www.whistler-blackcomb.com/weather where there is also a link to the CAA public avalanche bulletin, or call 1-800-667-1105.

– Whistler Mtn. Snow Safety

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