Our persistent weak layer is sensitive and will continue to be a concern with the warm weather. Dangerous avalanche conditions exist and rider-triggered avalanches are likely.
Reactive wind slabs are easy to trigger by riders. Small wind slab releases may step down to weak layers in the upper snowpack to produce larger, more destructive avalanches.
Recent snow and wind have been working to consolidate reactive slabs over the mid-February weak layer and the late January crust below it. Shaded, wind-loaded areas at higher elevations are the most likely places to trigger this problem.
Since Sunday, numerous large natural avalanches (size 2.5 to 3) were observed from steep northerly slopes at treeline and above. Several skiers-remote persistent slabs (size 1 to 2) were reported on the persistent layers down 40 to 50 cm deep while large triggers (vehicle and helicopter) remotely triggered large slabs (up to 100 cm crown). There are mentions of multiple sympathetic releases and recent step-down avalanches.
The region received 20 to 30 cm of recent snow since Sunday, bringing the storm total to 50 to 60 cm. This is overlying various problematic surfaces including weak surface hoar or faceted grains in sheltered, shaded terrain, and sun crusts on sun-affected slopes. This layer was responsible for numerous and large remote triggers observed since Sunday throughout the region.
A layer of hard crust, buried in late January, is currently sitting beneath weak facets and less widespread surface hoar 40 to 80 cm deep. Some recent avalanches have failed on it, particularly closer to Whistler.
The snowpack below is strong.
Tuesday Night
Mostly cloudy with isolated flurries. 15 to 25 km/h southwest ridgetop wind. Treeline temperature -3°C. Freezing level lowering from 1700 to 1000 m.
Wednesday
Mostly sunny. 30 to 40 km/h southwest ridgetop wind. Treeline temperature +2°C. Freezing level reaching 2200 m.
Thursday
Cloudy with isolated flurries. 40 to 50 km/h southwest ridgetop wind. Treeline temperature +2°C. Freezing level reaching 2000 m.
Friday
Mostly sunny. 15 to 25 km/h southwest ridgetop wind. Treeline temperature +2°C. Freezing level reaching 2200 m.
More details can be found in the Mountain Weather Forecast.
