Avalanche Forecast

Issued: Mar 1st, 2012 8:49AM

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

Avalanche Canada ccampbell, Avalanche Canada

Summary

Confidence

Fair - Intensity of incoming weather is uncertain for the entire period

Weather Forecast

Friday: Light flurries with strong westerly winds and freezing levels near valley bottoms. Saturday: Light to moderate snow with 10-20cm possible by the end of the day. Continued strong westerly winds and freezing levels rising throughout the day to 1800m by the evening. Sunday: Continued light flurries or rain at lower elevations with freezing levels as high as 2000m.

Avalanche Summary

Recent explosive control throughout the region produced results up to Size 2.5 on the mid-February persistent weakness. The 20-50cm slabs were very touchy with some wide propagations.

Snowpack Summary

A cohesive slab continues to settle over the mid-February surface hoar, which is generally down in the 40-55cm range. Recent reports include whumpfing and cracking, and moderate but sudden compression test results. This persistent weakness is susceptible to remote triggering and has the ability to propagate in low angled terrain, and the overlying slab structure creates the potential for step-down avalanches. Basal facets have only been reactive on steep, shallow, and rocky slopes, but operators continue to monitor this layer in tests. Triggering this deep persistent weak layer is unlikely, but shallow snowpack areas or shallow weak areas adjacent to deeper wind loaded slopes are the most suspect locations.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Persistently weak buried surface hoar demands continued diligence and conservative decisions. The potential for remote triggering, step down avalanches, and wide propagations, makes this weakness particularly tricky to predict.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Wind Slabs

An icon showing Wind Slabs
Generally lurking below ridgecrests, behind terrain breaks, and in gullies. Fresh wind slabs are expected to be very touchy and continued strong winds over the forecast period is expected to overload weaknesses.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Mar 2nd, 2012 8:00AM

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