Avalanche Forecast

Issued: Dec 23rd, 2013 8:25AM

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

jlammers, Avalanche Canada

South Coast.

Summary

Confidence

Fair - Wind effect is extremely variable

Weather Forecast

Tuesday: Mainly cloudy / Light to moderate southwest winds / Freezing level at 700mWednesday: Flurries / Moderate southwest winds (with extreme gusts) / Freezing level at 1000mThursday: Light snowfall / Moderate southwest winds / Freezing level at 1600m

Avalanche Summary

Several remotely triggered size 1-1.5 soft slab avalanches were observed in the North of the region in the past few days. They occurred on a north/northeast aspect at treeline. The December 12th surface hoar layer was the culprit in these events.A size 1 soft wind slab was also ski cut in the north of the region on Sunday. It occurred on a north facing slope at treeline.

Snowpack Summary

Snowpack depths vary greatly across the region with 130cm reported at treeline in the Northern Cascades but only about 50 cm along the Duffy. In general, the snowpack across the region is significantly thinner than average for this time of year. Terrain below treeline is still mostly below threshold for avalanche activity.Very light (in the north of the region) to moderate (in the south of the region) amounts of recent snowfall now sit on a generally well consolidated snowpack. Previous weak interfaces within the snowpack appear generally well bonded and have been unreactive to recent snowpack tests. The exception to this seems to be in the north of the region where very touchy surface hoar buried on December 12th sits below about 30cm of recent snowfall. This will be a weakness to watch as the overlying slab develops. Early season riding hazards such as rocks, stumps and logs are lurking below the surface at treeline elevations and below.

Problems

Wind Slabs

Recent snowfall and strong southwest winds will have created stiff new windslabs in lee terrain. Although they may be gaining strength, they may propagate over wider distances, particularly in the south where recent accumulations were significant.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be alert to conditions that change with elevation.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Reports from the Duffey area indicate a touchy layer of buried surface hoar now sits under about 30cm of snow. This is likely the layer to watch as the overlying slab develops.

Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 24th, 2013 2:00PM