Explosive control work targeting cornices on Friday produced results up to size 2. On Wednesday, there were reports of a natural storm slab avalanche cycle up to size 3. There were also several that stepped down to deeper weak layers resulting in very large (size 3-4) persistent slab avalanches. Check out this MIN describing a large cornice-triggered avalanche in the Blackcomb sidecountry on Thursday.

Last Saturday, a large (size 3) avalanche was remotely triggered by skiers on Cowboy Ridge near Whistler. The avalanche occurred on a north to northwest aspect at around 1900 m. The crown ranged reached up to 200 cm and was approximately 200 m wide. Check out this MIN for photos and more information. A similar avalanche was remotely triggered by skiers on a nearby westerly slope a few days before; check out this MIN for more info and photos.

Variable wind effect in the alpine includes scoured windward aspects, sastrugi, hard slab, wind pressed surfaces over lower density snow and isolated pockets of soft snow in sheltered areas above 2000 m. Wind slabs may remain sensitive where they overlie surface hoar in sheltered terrain or a crust on solar aspects. A widespread surface crust exists below 1900 m.

The snowpack is currently quite complex. A layer of sugary faceted grains above a hard melt-freeze crust from early December may be found down 100 to 200 cm. Last weekend, several large natural and human-triggered avalanches on this layer occurred, with the hot spots being around the Whistler backcountry.

Near the base of the snowpack, there may be faceted grains above a crust from early-November, which was identified as the failure layer in recent sporadic avalanche releases. At this depth, avalanches are large and destructive.

Saturday night: Snow, 5-10 cm, light to moderate southwest ridgetop wind, freezing level 800 m.

Sunday: Mostly cloudy, light to moderate southwest ridgetop wind, freezing level 1100 m.

Monday: Sunny, light to moderate northerly wind, freezing level 1300 m with an above freezing layer developing around 2500 m.

Tuesday: Sunny, moderate southwest ridgetop wind, freezing level 1000 m, above freezing layer breaking down.

Natural cornice falls up to size 2 have been observed recently. Explosive control work on Friday produced wind slab avalanches up to size 2. 

A widespread natural avalanche cycle size 2-3 occurred throughout the region on Wednesday. Avalanche character was predominantly storm slab in the snowy north of the region and wet loose or glide slab in the rainy south. Northwest of Pemberton, several stepped down to buried weak layers resulting in very large (size 3-4) persistent slab avalanches.

• In the south of the region, fluctuating freezing levels during the last storm have resulted in a crust to ridgecrest. At upper elevations, 5-10 cm of dry snow has been blown around by the wind, exposing the crust in some areas and building wind slabs ontop of it in others. This MIN report from Nak Peak on Thursday depicts snow conditions changing with elevation.

• In the north, variable wind effect in the alpine includes scoured windward aspects, sastrugi, hard slab, wind pressed surfaces over lower density snow and isolated pockets of soft snow in sheltered areas. Wind slabs may remain sensitive where they overlie a spotty layer of surface hoar in sheltered terrain or a crust on solar aspects. A widespread surface crust exists below 1600 m.
• A melt-freeze crust from early December is found around 200 cm deep in the snowpack. This crust may have sugary faceted grains sitting above it. This persistent weak layer is most prevalent in the North, northwest of Pemberton where large avalanches have failed on this interface recently. This interface doesn’t seem to be a concern in the South (Coquihalla) and little information is known for the North Cascades or far South in Manning Park.

Saturday night: Flurries, trace, moderate to strong southwest wind, freezing level 800 m.

Sunday: Flurries, trace, moderate northwest wind, freezing level 1000 m.

Monday: Sunny, light northwest ridgetop wind, freezing level 1000 m.

Tuesday: Mix of sun and cloud, southwest ridgetop wind building to strong, freezing level 800 m.

No new avalanches. Glide cracks were observed to be opening up during the wet storm earlier in the week.

Around 10 cm of new snow falls on a thick block of icy rain crust which may be bridging a weaker layer of dry, sugary faceted snow. Affecting this weak snow through the thick crust would be difficult and avalanches on it are unlikely but not impossible in unsupported terrain. Below, the snowpack is a multi tiered sandwich of crusts and moist snow and is well consolidated.

Watch North Shore Rescue's weekly snowpack conditions update from Friday here.

Saturday night: Snow, 10-15 cm, light westerly ridgetop wind, freezing level 1100 m.

Sunday: Mostly cloudy, moderate northwest ridgetop wind, freezing level 1000 m.

Monday: Sunny, light northerly ridgetop wind, freezing level 2000 m.

Tuesday: Sunny, moderate westerly ridgetop wind, freezing level 2300 m dropping to 700 m.