Avalanche Forecast

Issued: Dec 16th, 2016 4:26PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs.

Avalanche Canada cam_c, Avalanche Canada

Beware of wind-loaded and sun-exposed slopes where the recent storm snow has settled into touchy slabs.

Summary

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

A mix of sun and cloud for Saturday with moderate northwesterly winds and alpine temperatures around -10. Sunday should be mainly cloudy with flurries bringing 10 cm of fresh snow by the afternoon. Ridgetop winds are expected to increase to moderate to strong westerlies and alpine temperatures around -10. Expect to wake up Monday morning with 15-20 cm of fresh snow in the mountains with an additional 5-10 cm throughout the day all falling under strong southwesterly winds. Freezing levels are expected to rise as high as 1200 m by Monday afternoon.

Avalanche Summary

On Sunday two skiers were caught in an avalanche on the North Shore on Sunday in steep, rugged terrain. There's a photo on the North Shore Rescue Facebook page. On Saturday, a size 1.5 skier triggered avalanche was reported on the MIN. The slab was 20-30cm thick and the avalanche was 30-40m wide. Other social media from the weekend indicated highly unstable conditions. With dry, cold weather, avalanches have become harder to trigger, but I'd urge caution, since the cold temps will prolong the possibility of skier-triggered avalanches longer than is usual for this region.

Snowpack Summary

Anywhere from 30 cm (near Squamish) to 75 cm (North Shore) of faceted powder overlies the variable old snow surface from late last week, which includes well settled snow on southerly aspects, loose snow on shaded aspects, isolated pockets of surface hoar, and sun crusts on steep southerly aspects. Recent easy to moderate sudden planar snowpack tests suggest poor bonds within and under the recent storm snow. Colder than usual temperatures and the potential for buried surface hoar means these weaknesses will take longer than normal to stabilize. An old rain crust is reported to be down 150 cm in the North Shore mountains. This layer is still failing on snowpack tests, but is likely difficult to trigger in most places now.

Problems

Storm Slabs

An icon showing Storm Slabs
Up to 75 cm of recent storm snow remains sensitive to human triggers and forecast winds are expected to build new wind slabs.
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.The new snow will require several days to settle and stabilize.Avoid freshly wind loaded features, particularly in steep terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 17th, 2016 2:00PM