Avalanche Forecast

Issued: Jan 30th, 2012 9:25AM

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

jlammers, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Freezing levels are uncertain on Thursday

Weather Forecast

Tuesday: light snowfall continuing through the evening / moderate southwest winds / freezing level at 1000m Wednesday: light snowfall in the morning with clearing by the afternoon / light southwest winds / freezing level at 1000m Thursday: clear / light southwest winds / freezing level climbing throughout the day to 1200m

Avalanche Summary

1 size 2 and numerous size 1 explosives-controlled avalanches were observed in the Whistler area on Monday.

Snowpack Summary

The region saw variable amounts of snow with moderate to strong winds and warmer temperatures on Sunday. The variable and cohesive windslabs that formed at treeline and in the alpine have strengthened somewhat, but could become reactive on unsupported features below ridgecrests. These new windslabs are resting on impressive amount of storm snow that fell last week. By now last week's storm snow should be well settled.About a metre down there are a variety of older snow surfaces that formed throughout January. These surfaces include facets, old wind slabs, and crusts. These interfaces have also gained considerable strength, but triggering may be possible with a heavy load in isolated terrain. Previous concerns about deeper persistent weak layers appear to have diminished.Snowpack depths at treeline are in the region of 260 cm.

Problems

Wind Slabs

Moderate snowfall amounts and strong winds have set up new wind slabs on lee slopes. Strengthening has occurred, but triggering is still possible on unsupported terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Storm Slabs

Heavy amounts of storm snow have fallen on a variety of old surfaces. A deeper release has decreased in probability, but would have a high consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 5

Cornices

Strong winds and new snow have added mass to sensitive cornices. They may be destructive by themselves, and may also be a trigger for the slope below.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 6

Valid until: Jan 31st, 2012 8:00AM