Avalanche Forecast

Issued: Jan 29th, 2012 9:32AM

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

jlammers, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Tuesday

Weather Forecast

Monday: very light snowfall / moderate southwest winds / freezing level at 700m Tuesday: light snowfall becoming moderate overnight / light to moderate southwest winds / freezing level at 900m Wednesday: light snowfall in the morning with a clearing trend developing in the afternoon / light to moderate west winds with rising freezing levels

Avalanche Summary

Numerous size 1 windslab avalanches were reported from the Whistler area in response to windloading on Sunday. Observations were limited due to poor visibility.

Snowpack Summary

The region saw variable amounts of snow with moderate winds and warmer temperatures on Sunday. The result is fresh, cohesive windslabs on lee features at treeline and in the alpine. These new windslabs are resting on impressive amount of storm snow that fell last week. By now I suspect that last week's storm snow has gained considerable strength.About a metre down there are a variety of older snow surfaces. These surfaces include lower density snow which may have had seen some faceting, old wind slabs, and crusts. These interfaces have most likely 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 moderate winds have set up new wind slabs on lee slopes. Rising freezing levels have added cohesion to wind slabs adding to the likelihood of wider propagations.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Storm Slabs

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

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 30th, 2012 8:00AM