Avalanche Forecast

Issued: Dec 17th, 2011 9:02AM

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

Avalanche Canada jlammers, Avalanche Canada

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Monday

Weather Forecast

Mostly clear skies are forecast for sunday morning with freezing levels at or near surface. Late in the day another frontal system will hit the region bringing 10-15cm of snow overnight and throughout monday. Moderate to strong southwest winds and freezing levels of 900m will accompany this system.Tuesday calls for light to moderate snowfall in the morning, cooler temperatures and reduced westerly winds.

Avalanche Summary

No new avalanches have been reported. This may speak more to lack of reports from the field than actual avalanche conditions. Any information (professional or recreational) from the field is highly appreciated. Please send your observations to forecaster@avalanche.ca.

Snowpack Summary

About 15 centimetres of new snow and surface hoar crystals are sitting on the less recent 20cm of storm snow which fell earlier in the week. This storm snow we received earlier this week sits on a variety of old weak snow surfaces including surface hoar, melt-freeze crusts and facetted snow. For the most part all aspects between 900m-2000m have a hard melt freeze crust. This crust is widespread and is lingering in most start zones. This is the layer of concern at the moment. Above this crust surface hoar (feathery crystals) and facets (sugary crystals) may be preserved. The recent winds in the alpine seem to have destroyed the surface hoar in exposed areas in the alpine eliminating that problem but creating a wind slab problem. In short, the upper snowpack is variable and a cautious approach is required as new slabs continue to form over the buried weak layers. The midpack seems to be well settled and strong.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs have developed on lee and cross-loaded terrain in the alpine and at treeline. Expect further development with monday's forecast weather

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Storm Slabs

An icon showing Storm Slabs
Expect general storm slab activity on a variety of aspects as the new snow gains cohesion and creates more load on buried weak layers

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 18th, 2011 8:00AM

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