Recent wind loading and reactive wind slabs are the primary concern. However, as the recent storm snow continues to settle, it will still be important to evaluate the bond between the old snow surface and the new snow.
Summary
Confidence
Moderate -
Weather Forecast
Lingering flurries are expected on Friday morning in the south of the region with mostly cloudy and dry conditions in the afternoon. Alpine winds are forecast to be light from the southeast and treeline temperatures are expected to be around -10C. Another period of light snowfall is possible Friday overnight with 0-3 cm expected. On Saturday, mostly cloudy conditions are expected with the possibility of lingering flurries in the morning and sunny breaks in the afternoon. Alpine winds are forecast to remain light but shift to a northeast direction and treeline temperatures are expected to be around -12C. On Sunday, mostly sunny conditions are forecast with light alpine wind and treeline temperatures around -15C.
Avalanche Summary
On Thursday, ski cutting triggered two size 1 cornices. These did not trigger slabs on the slopes below. On Wednesday, ski cutting produced two size 1 slab avalanches on small rolls at 1900 m elevation. These were 50 cm thick. A natural size 2 avalanche was also observed from Monday or Tuesday during the storm on a northeast aspect at 1700 m elevation. On Friday, the biggest concern remains areas where the recent storm snow has been redistributed into wind slabs. There is also still concern regarding the mid-December interface that was buried during the recent storm. It appears that in most places the recent storm snow is relatively low density and has not formed a slab over this interface. The only areas where this layer has been reactive is in wind loaded areas but I would continually watch for signs that a slab is developing in areas that have not been affected by wind.
Snowpack Summary
50-70 cm of new storm snow sits above a plethora of old snow surfaces including stiff wind affected snow, faceted (sugary) crystals and surface hoar crystals that formed in locations sheltered from the wind. The new storm snow was expected to bond poorly to these old surfaces; however, less avalanche activity than expected has been noted on this layer, indicating the bond may not be quite as poor as expected. The upper snowpack is still soft - as this becomes stiffer and denser, we may start to see more slab avalanche activity on this layer. The thick mid-November crust is now buried down 70-150 cm and produces variable results in snowpack tests. This layer is generally considered dormant at this time but remains an isolated concern that we will likely be tracking through much of the season.
rbuhler,
Avalanche Canada
