Avalanche Forecast

Issued: Dec 10th, 2011 8:52AM

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

Avalanche Canada mpeter, Avalanche Canada

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Sunday: Expect skies to clear over the course of the day, with winds turning northerly but remaining light. Temperatures could reach -10. Monday: Winds turn westerly but remain light under continued clear skies. Tuesday: Expect clouds to build and flurries to begin late in the day under southwesterly winds. The western slopes will likely see higher accumulations, up to 10cm.

Avalanche Summary

As folks take advantage of the clear weather to get further afield we have reports of old avalanches that released on the persistent weakness deep in the snowpack. The most recent events have been isolated to small, loose sluffs on steep south facing terrain associated with the recent daytime warming.

Snowpack Summary

Some areas have seen a trace of new snow (less than 5cm), but beyond this the region has seen little change. Surface hoar continues to grow in sheltered locations and the cold temperatures are penetrating the upper snowpack to promote near surface facetting. There is some sun crust formation on steep south through west aspects. Hard windslabs linger in the alpine and open treeline locations but are softening due to the facetting phenomena. Some areas have a rain-crust below treeline from the 28th of November that has been buried by about 20 cms of snow. This rain-crust may be developing facets, and could become a layer of interest after it is buried by more of a load.The early November surface hoar remains a layer of concern. It is buried 100-150 cms and stability tests show that this layer is getting harder to trigger. However, if an avalanche does release on this layer, it is likely to be very large and destructive.

Problems

Wind Slabs

An icon showing Wind Slabs
Old windslabs still lurk in lee locations at ridgecrest. Be aware of the new snow hiding these old slabs or forming into new soft slabs with the forecast of moderate winds.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Probability of triggering has decreased. Where it still exists, this layer may be capable of producing highly destructive, full depth avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Dec 11th, 2011 8:00AM