Avalanche Forecast

Issued: Jan 3rd, 2012 9:06AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Good - -1

Weather Forecast

Wednesday: Mix of sun and cloud. Light precipitator today up to 5mm. Ridgetop winds from the SW 70-100km/hr. Freezing levels rising to 2000m throughout the day. Thursday: Snow amounts up to 5cms in the morning. Ridgetop winds from the West 55-70km/hr. Freezing levels falling back to valley bottom midday. Friday: Mix of sun and cloud. Freezing levels remain near valley bottom. Ridgetop winds light-moderate from the SW.

Avalanche Summary

On Monday a skier triggered a size 2 slab avalanche in the Harvey Pass area. A wind slab from the ridgecrest was triggered, then stepped down 55cms to a weak surface hoar/ facet layer beneath the surface. Please visit our incident report database on our website for more details @ avalanche.ca.

Snowpack Summary

The CAC Field team headed to Harvey Pass on Tuesday and completed a fracture line profile on yesterday's skier triggered avalanche. The total HS (height of snow) in that area is 180cms. A stiff wind slab was triggered and stepped down 55cms to the mid-December surface hoar/facet layer. Compression tests done showed hard results, but sudden planar characteristics. I suspect you can find this buried layer to the West of the divide in most locations. As soon as you travel to the east surface hoar is spotty, and/or non-existent. The snowpack to the east is 100-120cms in depth, and widespread wind slabs have formed lee to the SW in upper elevations. Many windward areas are scoured. The mid pack is generally well consolidated. At the bottom of the snowpack 20cms of 4F facets and depth hoar exist.

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
Warm temperatures may consolidate the snow above the surface hoar into a slab that may propagate wide avalanches. This mid-December surface hoar/ facet layer is found mainly in the Western parts of the region.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 6

Valid until: Jan 4th, 2012 8:00AM