Backcountry Advice 

As of Wednesday, Dec. 20

Alpine: CONSIDERABLE trending to HIGH

Treeline: MODERATE trending to CONSIDERABLE

Below Treeline:  LOW trending to MODERATE

Travel Advisory:  High winds accompanied the 50cm of snow that fell last Friday night, as well as the 10cm that fell on Monday night, and they are expected to accompany tonight’s snowfall as well. Many new features have developed with the high wind events during the past week, so take it easy if you are traveling in low visibility conditions.

Avalanche Activity: Explosive testing and ski cutting carried out last weekend produced up to size 2.5 results with crown lines varying maxing out at 100cm in depth. In some areas the bed surface was observed to be a thin melt-freeze crust that formed on Dec. 6 th . Sunday night’s renewed windslab development was observed on Monday and Monday night, with some pockets up to 40cm in depth reacting to stability testing, with limited propagation. Bear in mind that in some isolated areas a surface slab in motion may have the potential to trigger a deeper release within last week’s storm snow layers, resulting in a potentially large and destructive avalanche.

Snowpack: The distribution of snow has been extremely variable due to the strong winds that have accompanied the past few snowfalls. In the high alpine terrain a 1-finger stiff windslab overlies a pencil stiff windslab, with yet another windslab expected to form on top of this tonight. On some windward slopes the Dec. 6 th melt-freeze crust is still exposed on the surface. Be wary of rocky terrain where a failure at a weak point on the slope could pull into the fat part of the slab and produce a sizeable avalanche. The layer of surface hoar that formed on Saturday night remains intact in some sheltered areas at and below the treeline. This could be a layer to watch for as it receives additional loading.

Weather: The system that is arriving onshore today is expected to bring moderate to heavy snowfall tonight, and then taper to flurries on Thursday. Strong mountaintop winds can be expected to develop tonight as they switch from the SE to the SW, with freezing levels falling from 1,200 metres to close to the valley bottom. Friday may be a dry day, but the extended outlook is currently looking like continued cool and unsettled weather into the Christmas holidays.

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 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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