Avalanche Forecast

Issued: Mar 13th, 2012 11:03AM

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

Jlammers, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Wednesday: light snowfall - strong southwest winds - freezing level at 700m Thursday: moderate to heavy snowfall (starting Wednesday evening and continuing throughout Thursday) - strong southwest winds - freezing level at 1100m Friday: light snowfall - moderate southwest winds - freezing level at 800m

Avalanche Summary

Recent avalanche observations have been fairly limited due to inclement weather. Having said that, explosives controlled and natural avalanches to size 2.5 were reported having reacted on a variety of aspects. Mostly storm instabilities were observed; however, in some cases avalanches stepped down to persistent weaknesses buried in early February. A size 3 cornice collapse was also reported from the region.

Snowpack Summary

Recent snow accumulations have been variable throughout the region, but mostly moderate daily accumulations and moderate to strong winds have been responsible for extensive wind transport at higher elevations, and recently developed wind slabs now exist at treeline and in the alpine. In the mid snowpack lies the mid-February surface hoar. Buried well over a metre down, this surface hoar may exist in combination with crusts or facets. These persistent weaknesses have remained reactive 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

Wind Slabs

New snow and moderate to strong winds have continued to form reactive wind slabs on lee features. Large cornices may also act as a trigger on slopes below.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Persistent Slabs

Persistent weaknesses are buried upwards of 150cm below the surface. Surprisingly large avalanches could be triggered naturally by the weight of additional snowfall, or by the energy of a person/sled.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 7

Storm Slabs

With ongoing snowfall, storm slabs have formed on all aspects and elevations. Surprisingly large, destructive avalanches will occur if storm slabs step-down to a persistent weak layer buried below.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Mar 14th, 2012 9:00AM