Whistler avy report Dec 31
For all the guys out there who avy skills consist of "That slope has never slid before" you better check what I have put in bold at the bottom.
Backcountry Avalanche advisory
December 31, 2007
Alpine: Moderate
Treeline: Moderate
Below Treeline: Low
Travel Advisory: Cold low density snow has slowly been loading over settling soft slabs, but all those rocks and exposed crusts are still out there. Moderate to strong winds Saturday night from the SE and SW formed some soft windslabs in the alpine that were easily reacting to a ski cut. Cornice tabs have also grown and they are fragile as well. The Dec 4th rain crust is buried anywhere from 60-150cm deep on some lee slopes, but it can still be found on the surface at ridgelines and on some windward slopes.
Avalanche Activity: Size one soft windslabs were easily triggered yesterday morning. They were propagating widely, with crowns averaging 10-20cm in depth. It seemed that the slab became particularly reactive lower in the alpine elevations. Last week several size two slabs stepped down an average of one meter to the Dec 4 crust and facet layer that is buried from 0.6 to 1.5 meters below the surface. As previously noted, Saturday night’s wind formed lots of new cornice tabs that are breaking easily.
Snowpack: In the alpine terrain a soft windslab is sitting on underlying layers of less dense storm snow. As you drop below treeline there is no slab. The December 4th facet crystal and raincrust 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 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 natural avalanching occurring. 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 a mix of sun and cloud today with increasing cloud and snow beginning overnight. A system tomorrow will be the first in a series that will bring heavy snowfall and warming temperatures for the remainder of the week.