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Avalanche Forecast

Dec 9th, 2012–Dec 10th, 2012
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
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
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Sea To Sky.

Confidence

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

Weather Forecast

Overnight and Monday: A weak ridge of High pressure is forecast to bring moderate gusty NW winds overnight that should decrease during the day as the flow shifts more Westerly. The Westerly winds are expected to increase to moderate Monday evening. Very light precipitation overnight and none forecast for Monday.Tuesday: A cold front is expected to move down the coast from the North sometime Monday night, bringing 8-12 mm of precipitation that should fall as snow at all elevations. Expect SE 20-30 km/hr at ridge tops.Wednesday: There is another system forecast to move onto the coast in the afternoon. Timing, precipitation amounts, and wind values are uncertain at this time.

Avalanche Summary

Some thin wind slabs were ski cut up to size 1.0 that were 20 cms deep. Explosives control released a size 2.0 in steep un-skiable terrain.

Snowpack Summary

Some exposed areas have developed a thin stiff wind slab in the alpine. Sheltered areas have 20-30 cms of light unconsolidated snow above a gradually stiffening snowpack. Snowpack tests have not been showing any consistent results in the storm snow. Foot penetration may still be up to 70 cms as the wind slab is not able to carry the weight of a person without skis. Professionals are concerned about the early November rain crust. If this deep persistent weak layer (DPWL) becomes reactive, the consequences will be very large destructive avalanches. The crust may be buried between 100-200 cms depending on the total depth of the snowpack in your area. The crust may be a bigger problem where it has a layer of facetted crystals above, rather than where it is like a laminated sandwich of crusts and facets. If that sounds too technical for you, then the take home is that this is not an easy problem to gauge when or where it might wake up.

Avalanche Problems

Wind Slabs

New wind slabs are expected to continue to be triggered by heavy additional loads. NW winds may cause some reverse loading on Southerly facing slopes.
Avoid freshly wind loaded features.>Avoid travelling in areas that have been reverse loaded by winds.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 5