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Archived

Avalanche Forecast

Jan 1st, 2013–Jan 2nd, 2013
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Wednesday: Moderate snowfall (up to 10cm) expected near the coast, tapering off rapidly with distance inland, meaning many areas likely to stay dry. Freezing levels around 1000 m. Strong ridgetop winds gusting in excess of 80 km/h from the SW.Thursday: Up to 10cm new snow, again focussed along the coast.  Freezing levels remaining around 1000 m. Ridgetop winds 60-80km/h.Friday: Light snowfall, Freezing levels dropping to around 500 m. Winds becoming moderate southerly.

Avalanche Summary

On Monday, avalanches up to size 2 were observed in the recent storm snow at all elevations. Although they appeared to only affect the top 10-20 cm of the snow surface, they were reported to be running far. Sluffing on steep terrain has also been reported.

Snowpack Summary

The recent new snow was warmer and denser in places than the existing snow on the ground, helping to create touchy storm slab conditions. The upper slab, while generally thin, was highly reactive in many places on Monday. Winds marked a significant shift from mostly light northerly to a period of strong south southwesterly to southeasterly. These have set up touchy wind slabs in many exposed lee areas. There are two surface hoar layers in the upper snowpack. The upper one formed at the end of December and is buried approximately 30 cm below the surface. Professionals have reported easy, sudden planar compression test results on this layer and it has been reactive to skier-triggering. The lower one formed at the beginning of December and is buried approximately 90 cm below the surface. Hard, planar compression tests have been reported on this layer. Near the base of the snowpack, a crust/facet layer continues to give hard, sudden results to no results in snowpack tests. This weakness is unlikely to be triggered by a single person, but it remains possible with a very heavy load (e.g. cornice fall) or from a thin-spot trigger point.

Avalanche Problems

Persistent Slabs

Choose well supported terrain without convexities.>Use safe ski cutting techniques before entering ski run. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Loose Dry

Loose dry avalanches will be easily triggered on steep terrain and in sheltered areas.
Be cautious of sluffing in steep terrain.>Sluffs may trigger deeper instabilities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Wind Slabs

Strong SW to SE winds have set up touchy new wind slabs in exposed lee terrain. The bond to the old snow surface is poor and comprises facets and/or surface hoar in some places.
Avoid freshly wind loaded features.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Stay well to the windward side of corniced ridges.>

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

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 5