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Avalanche Forecast

Mar 9th, 2012–Mar 10th, 2012
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Cariboos.

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.

Avalanche 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