Avalanche Forecast

Issued: Dec 13th, 2011 8:38AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

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

Weather Forecast

Wednesday: Flurries expected in the evening with light - moderate ridgetop winds from the north east. Thursday: A mix of sun and cloud during the day. Treeline temperatures near -10. Winds light from the north east. Thursday Night: Moderate - heavy snowfall amounts are in the forecast. Freezing levels could rise to 700m.

Avalanche Summary

Numerous natural avalanches up to size 2 occurred overnight Monday with the new snow and wind. Explosive avalanche control work also produced numerous size 2 avalanches on east-south east aspects.

Snowpack Summary

The southern part of the region has received up to 40cm of new snow (Kasiks, Terrace areas) and less snowfall to the north. This is forming storm slabs at all elevations. This new snow is being blown around by strong southwest winds creating new wind slabs on lee slopes. The upper snowpack consists of a variety of weak snow surfaces (surface hoar, melt-freeze crusts, and facetted snow) which are currently being buried. Once these layers reach their threshold natural and rider triggered avalanches will occur. Most operations in the region have reported large surface hoar (feathery type snow crystal) that is sitting on a thick melt-freeze crust. This crust is up to 20cm in thickness and extends up to alpine elevations in the south, and around 1000m in the north. A strong temperature gradient in the top 30cm was reported to be faceting snow below the surface crust.The mid and lower snowpack are generally well settled and strong.

Problems

Wind Slabs

An icon showing Wind Slabs
Expect new wind slabs on north through east aspects. Loading may occur lower on the slopes due to forecast high winds in some parts of the region.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Storm Slabs

An icon showing Storm Slabs
Storm slabs will continue to form with forecast snow. Pay attention to the snowfall amounts in your local area, they may vary through the region. More snow = thicker slabs. They can run far, fast and be destructive.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Dec 14th, 2011 8:00AM

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