Avalanche Forecast

Issued: Dec 22nd, 2012 9:28AM

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

jlammers, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Mainly clear skies are expected for the forecast period. Expect temperature inversions with ridgetop temperatures of about -14.0. Winds should be mostly light and southeasterly with strong northeasterly outflows.

Avalanche Summary

Several size 2 avalanches were reported from the far north of the region. They failed at the ground on shallow, south-facing terrain. No other recent avalanches have been reported

Snowpack Summary

Light amounts of recent snow have been redistributed by strong winds into mainly stiff windslabs. This overlies older storm snow which has most likely settled and gained significant strength. In the mid snowpack you might find a buried surface hoar layer, reported to be 5 to 10mm in size. Last week it produced sudden snowpack test results down 60-80cm in the Shames backcountry, and may exist in other areas as well. In the far north there have been reports of faceted crystals in the top metre of the snowpack producing moderate to hard test results.At the base of the snowpack a faceted crust remains on the radar of avalanche professionals, particularly in the north of the region. It seems this problem is mostly confined to alpine areas and likely needs a large trigger and/or a shallow snowpack feature. Cornices are also large. Continued strong winds and cooling temperatures could make them especially heavy and brittle.

Problems

Wind Slabs

Light amounts of new snow have been redistributed by strong winds into wind slabs on a variety of aspects. These new wind slabs are adding to older storm snow accumulations which have most likely gained considerable strength.

Be cautious as you transition into wind affected terrain.>Watch for hollow sounds or shooting cracks as an indication of an instability..>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

Deep persistent weakness seem more problematic in the north of the region. Watch for triggering in thin, rocky, unsupported terrain.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 5

Valid until: Dec 23rd, 2012 2:00PM