Avalanche Forecast

Issued: Mar 9th, 2012 10:06AM

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

Jlammers, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Saturday: Light snowfall - Moderate southwest winds - Freezing level at 800m Sunday: Light to moderate snowfall - Moderate to strong southwest winds - Freezing level at 1000m Monday: Light snowfall - Moderate southwest winds - Freezing level at 700m

Avalanche Summary

Avalanche observations were very limited on Thursday; however, natural avalanches to size 2.5 were observed on Wednesday. It is suspected that cornice fall was the trigger for a size 3.5 slab on a west facing alpine feature. Several skier-triggered size 1.5 avalanches within the recent storm snow were also reported in the region. The possibility of deep and destructive avalanches will persist throughout the forecast period.

Snowpack Summary

Last weekend 60-100 cm of snow fell in the region. Strong winds and fluctuating temperatures with this system created the perfect recipe for storm and wind slabs. This recent snowfall added to the metre or so that overlies the mid-February surface hoar. This surface hoar may exist in combination with crusts or facets.These persistent weaknesses have remained reactive all week and are an ongoing concern at all elevations as avalanches may be unexpectedly large, and destructive. Large cornices have formed and could also act as a trigger on the slope below.

Problems

Persistent Slabs

Persistent weaknesses are buried up to 150cm below the surface. Surprisingly large avalanches could be triggered naturally by smaller avalanches, or by additional weight of a person/sled. Buried persistent weaknesses are tricky to predict.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 7

Storm Slabs

Recent snow and fluctuating temperatures have formed storm slabs. These overlie the deeply buried mid-February weak layers. Storm slabs that trigger this interface could create surprisingly large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 6

Wind Slabs

Strong winds have created wind slabs, even at treeline elevations. Large cornices may also act as a trigger on slopes below.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Mar 10th, 2012 8:00AM