Avalanche Forecast

Issued: Dec 21st, 2012 9:49AM

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

jlammers, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Saturday: Mostly clear skies / Moderate southeast winds / Temperature inversion with ridgetop temperature of -12.0Sunday: Mostly clear skies with trace amounts of new snow / Moderate southeast winds / Temperature inversion with ridgetop temperature of -13.0Monday: Trace amounts of new snow / Light southeast winds / Ridgetop temperature of -16.0

Avalanche Summary

An explosives controlled size 2 cornice fall/ windslab was reported from the region on Thursday. No other avalanches have been reported.

Snowpack Summary

Light amounts of new snow have been redistributed by winds at higher elevations. This overlies the past week's storm snow which has most likely settled and gained significant strength. A buried surface hoar layer, reported to be 5 to 10mm thick, has produced sudden snowpack test results down about 80cm in the Shames backcountry, and may exist in other areas too. Avalanche professionals continue to monitor a faceted crust near the ground which has been reactive this week in the Bear Pass area. It seems this problem is confined to alpine areas and likely needs a large trigger and/or a shallow snow pack feature to trigger. Cornices are also really big and forecast 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.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A persistent weak layer of surface hoar, buried 60-80 cm below the surface has been reported from around Shames. Although triggering seems less likely, watch for convex rolls in sheltered areas where the SH may have been preserved.

Use caution on open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Dec 22nd, 2012 2:00PM