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Avalanche Forecast

Mar 4th, 2012–Mar 5th, 2012
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
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

Regions: Cariboos.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Monday: A cold front brings moderate snow overnight Sunday. This is forecast to continue on Monday until the front departs in the afternoon. Moderate to strong westerly winds, switching to north-westerly and decreasing. Freezing level falling to valley floor.Tuesday: A brief ridge of high pressure should bring a break in precipitation and possibly clear skies and sunshine, although northern areas will probably cloud over by afternoon. Light winds and cool temperatures.Wednesday: Light snow. Increasing westerly winds.

Avalanche Summary

A natural avalanche cycle is under way, however poor weather is limiting observations. Natural, skier-remote and accidental avalanches were observed on Sunday to size 2. Avalanches reported throughout the week illustrate the unpredictable nature of persistent weak layers in the upper snowpack. On Thursday, a skier triggered a size 2.5 slab very easily and very close to recent ski tracks, which failed on buried surface hoar. On Wednesday, a cornice fall triggered a size 2 slab on a north aspect, which failed on the Feb 16. weakness. On Tuesday, numerous size 2-3 avalanches ran naturally, or with a remote trigger, on a variety of slopes. Most failed on upper snowpack persistent weaknesses. These layers are touchy and are likely to fail under the new storm load, creating large or widely-propagating avalanches.

Snowpack Summary

40-80cm snow has fallen, with snowfall forecast to continue until Monday. Strong winds and fluctuating temperatures are creating storm slabs and wind slabs on a widespread basis. Persistent weak layers buried in February are a key concern at all elevations and could be easily triggered by storm slabs, wind slabs or sluffs, or with a light additional load (like a sled or skier). Avalanches may be unexpectedly large, given the amount of fresh snow. Large cornices also loom as potential triggers for deep avalanches.

Avalanche Problems

Storm Slabs

Snow is falling with fluctuating temperatures, creating weak storm slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 6

Wind Slabs

Large amounts of available snow and strong winds are creating widespread wind slabs, even at treeline. Large cornices also threaten many slopes.

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

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 7

Persistent Slabs

Persistent weaknesses in the upper snowpack are unpredictable and tricky to manage. They are becoming more reactive as storm snow overloads them. Be aware of the potential for surprisingly large, wide avalanches at all elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 7