Below Treeline: CONSIDERABLE
Travel Advisory: We have received 20 cm of new snow during the past 24 hours accompanied by strong East and South-Easterly winds. You can expect to encounter soft wind slabs varying from 20 to 80 cm in depth in some start zones and to the lee of some terrain features. The Dec. 4th rain crust is well buried in most locations with the exception of some ridgelines and on some windward slopes.
Avalanche Activity: Avalanche control conducted this morning was producing up to size 2.0 avalanche activity with crown lines from 20 to 80 cm in depth with widespread propagation. Most of the activity observed was in the alpine, with some activity observed at treeline elevations as well. Rising temperatures in the valley will likely result in some avalanche activity today below the treeline in some steep gullies and drainages. Bear in mind that an avalanche in motion or a cornice fall could possibly trigger a deep slab release on the Dec. 4 crust and facet layer in some isolated areas.
Snowpack: In the alpine terrain a soft wind slab is sitting on underlying buried layers of wind slab, as well as areas of lighter density snow in more sheltered terrain. The Dec. 4th facet crystal and rain-crust weakness is gradually getting buried deeper, but the crust can still be found on the surface in some wind affected terrain. These layers may be a persistent weakness in some areas well into the season. Shallow rocky terrain is facetted as well, and failures there could propagate into the deeper instabilities. The forecast heavy snowfall and warming temperatures this week will be the first real test of these weaknesses, and you can expect to see some significant natural avalanching to occur. Given the depth of the instability, the avalanches have the potential to run full path to threaten the usually safe valley routes.
Weather: We can expect flurries to continue throughout the day today. Another series of systems is forecast to arrive Thursday bringing periods of heavy snowfall and strong winds at times right through the weekend. Friday may see a brief spike in the freezing levels, with a general cooling trend through the weekend and into next week.
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