Continue to choose conservative terrain and watch for clues of instability as storm snow and strong winds continue to incrementally load the snowpack throughout the day.
Avoid lee and cross-loaded terrain. Minimize exposure to avalanche terrain during times of heavy loading from wind and new snow.
Flurries begin again Thursday morning, slowly adding more load to the snowpack once again. In all exposed areas, new snow and strong southwesterly winds are building deep pockets in less that are reactive to natural and human triggers. Avoid lee and cross-loaded slopes.
If triggered wind slab avalanches may step-down to deeper weak layers and initiate large and destructive avalanches.
Recent large persistent slab avalanche observations are strong evidence that these layers are still an active concern in this region. Numerous problematic weak layers exist in the top meter of the snowpack. Be cautious around steep openings within and near treeline elevations as active loading continues.
A layer of large and weak facets sits near the base of the snowpack. This layer is most prominent in upper treeline and lower alpine elevations. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain. This layer has recently produced very large natural avalanches see avalanche summary for more information. Your best defence is to stay diligent in choosing low-consequence terrain away from overhead exposure.
On Tuesday, a skier accidental, size 1.5 storm slab avalanche was reported at 1500 m. A size 2, natural windslab avalanche was observed on a northwest aspect at 1400 m.
On Monday, a natural wind slab avalanche, size 2 was observed on a northerly aspect at 1900 m.
On Sunday, three very large natural avalanches were observed up to size 4. Two were size 3 persistent slab avalanches on steep north-facing aspects with 750 m wide crowns. A size 3.5-4 deep persistent slab avalanche was also observed. It is suspected this avalanche failed in depth hoar at the base of the snowpack.
See more on the potential of triggering deeper weak layers in our latest Forecasters' Blog.
Flurries begin again Thursday morning building upon 60 to 110 cm of storm snow from the last week. The storm snow sits on previously wind-affected surfaces. Below this, a melt-freeze crust is found on sun-exposed slopes and everywhere below 1600 m.
Several crust/facet/surface hoar layers exist in the upper and middle portions of the snowpack. The most concerning persistent weak layer is at the base of the snowpack from large and weak facets formed in November. This layer is widespread and most likely problematic in steep, rocky alpine and upper treeline terrain.
Wednesday Night
Partly cloudy. Ridge wind southwest 40-50 km/h. Alpine temperatures -10 C. Freezing level valley bottom.
Thursday
Partly cloudy with scattered flurries, 5-10 cm through most of the region. Up to 20 cm accumulation in the Pine Pass area. Ridge wind from the southwest 50 km/h picks up to 70 km/h in the evening. Alpine temperatures rise to -3 C. Freezing level 1400 meters.
Flurries continue through the night, 5-10 cm accumulation
Friday
Partly cloudy with isolated flurries, 5-10 cm accumulation. Alpine temperatures rise to -2 C. Ridge wind southwest 40-50 km/h. Freezing level 1300 meters.
Saturday
Partly cloudy with isolated flurries, 5-10 cm accumulation. Alpine temperatures rise to -3 C. Ridge wind southwest 40-50 km/h. Freezing level 1000 meters.
More details can be found in the Mountain Weather Forecast.
