Avalanche Forecast

Issued: Feb 14th, 2012 9:04AM

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

Avalanche Canada triley, Avalanche Canada

Summary

Confidence

Good - -1

Weather Forecast

Temperatures should drop down to about -12.0 in the alpine by Wednesday morning. The ridge of high pressure is expected to continue to bring clear skies and light winds during the day Wednesday. Alpine temperatures may rise above freezing on solar aspects, but should remain slightly below freezing on shaded aspects. Cloud should move into the region overnight and precipitation is expected to begin by about noon on Thursday. Western parts of the region may get 5 cm combined with moderate southerly winds. The freezing level should rise to 900 metres during the day and drop back to near valley bottom overnight. Another ridge is forecast for Friday that should bring mostly clear skies and light winds during the day.

Avalanche Summary

One size 2.0 explosive controlled release did release a piece of cornice that triggered the slope below down to the ground. One operator reported that a large natural ice fall released and did not trigger the slope below.

Snowpack Summary

Widespread surface hoar has been buried by a couple of cm of new snow in most of the region. A melt-freeze crust has developed on southerly aspects at all elevations. North and east aspects continue to have dry snow and some surface hoar sloughing in steep terrain. The January 13th surface hoar layer is buried about 40 cm below the surface, and may still be reactive in thinner snowpack areas. Basal facets have not been reactive, 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 suspect locations.

Problems

Cornices

An icon showing Cornices
Watch for tender cornices at ridge tops. They may be destructive by themselves, and have potential to trigger large avalanches on the slope below.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Although a deep persistent slab would most likely require a large trigger, they are still possible; especially in thin snowpack areas or in unsupported, rocky terrain.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

3 - 7

Valid until: Feb 15th, 2012 3:00AM

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