Avalanche Forecast

Issued: Jan 5th, 2012 9:00AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

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

Weather Forecast

A ridge of high pressure will continue to keep the region dry and cool through to Saturday. Mountain top winds will be from the NW at 30km/hr. A frontal system will push inland Saturday night bringing strong Chinook conditions with strong winds, and very mild temperatures on Sunday.

Avalanche Summary

A natural size 2 avalanche was reported on Mt. Fernie today at 1950m. The crown depth was 30-50cms, the width was 100m, and the running length was 500m. Two separate skier triggered avalanches were reported Tuesday from the Hartley Creek drainage. Both being slab avalanches size 1 on a NE aspect and the other on an East aspect, between 1850m-2150m. Both avalanches were reported as soft slabs failing on the mid-December layer. No injuries reported. On Monday a skier triggered a size 2 slab avalanche in the Harvey Pass area. Initially a wind slab from the ridgecrest was triggered, then stepped down 55cms to a weak surface hoar/ facet layer beneath the surface. Explosive control testing produced a size 1.5 slab avalanche on a NW aspect at 1900m. Please visit our incident report database on our website for more details @ avalanche.ca.

Snowpack Summary

The average HS (height of snow) in the Crowsnest North is 120cms and the Crowsnest South has 150cms. In the alpine and exposed slopes at treeline the windward aspects have been stripped of snow, and the lee slopes have widespread stiff wind slabs. As we move further West into the Elk Valley North the HS is an average of 130cms. The Elk Valley South sits at 170cms. Weak buried surface hoar layers can be found on North-NE slopes at treeline and below down approx. 30-40cms. In the Flathead the avg. HS is 170cms. This area also sees buried surface hoar on N-NE slopes. All snow depths indicated are at a 2000m elevation. The CAC Field team headed to Harvey Pass on Tuesday and completed a fracture line profile on a skier triggered avalanche. A stiff wind slab was triggered and stepped down 55cms to the mid-December surface hoar/facet layer. Compression tests done showed easy results with sudden planar characteristics. This shows this layer is still touchy to human triggers. The mid pack is generally well consolidated. At the bottom of the snowpack a variable facet/ crust/ facet sandwich is located with depth hoar up to size 5 below the crust, and facets size 2 above.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs can be found on North through Southeast aspects. Cross-loading is possible on open slopes oriented parallel to the wind. You may find wind slabs further down the slope or on open wind exposed areas below treeline.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
A cohesive slab sits over a touchy surface hoar weakness buried in mid-December. This layer is still touchy and susceptible to rider triggers. Avalanches on this layer will be large, destructive and may fracture across surprisingly far distances.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 6th, 2012 8:00AM

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