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Archived

Avalanche Forecast

Mar 5th, 2012–Mar 6th, 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
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
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 on Wednesday

Weather Forecast

Clear skies and cold temperatures are forecast for Monday night. Cloud should start to build during the morning as the wind veers to the west and increases to moderate. Expect about 10 cm of snow Tuesday afternoon and another 10 cm by Wednesday morning. Wednesday is expected to be unsettled with flurries, moderate winds, and rising freezing levels. A warm front should move in from the Pacific on Thursday bringing strong southerly winds, high freezing levels, and heavy precipitation.

Avalanche Summary

Some natural activity was reported from Sunday to size 1.5 on steep solar aspects in the afternoon. A couple of natural dry slab avalanches were reported from the Bear Pass highway corridor that were up to size 2.5 and may have been cornice triggered. Also, a couple of skier controlled and one skier remote triggered avalanche were reported releasing in isolated windslab pockets that were about 30-40 cm deep.

Snowpack Summary

Windslabs should be settling and bonding. There is between 70-100 cm of snow above the buried weak layer of decomposed and fragmented crystals that has been giving moderate shears in stability tests. Some areas are reporting a buried surface hoar from early February that is buried at the same depth. The weak layer may be triggered by light additional loads at treeline and below. This interface is variable, it consists of a strong melt freeze crust below 1000m, above 1000 m exists facets, surface hoar (in more sheltered areas), sun crust or wind press. The surface hoar is not widespread but is responsible for much of the larger avalanches that occurred recently. Areas below treeline are quite variable. There are spring like conditions with a melt-freeze crust in some areas, and others are still experiencing winter at lower elevations.

Avalanche Problems

Wind Slabs

Windslabs may take a couple of days to settle and bond.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 4

Persistent Slabs

A persistent weak layer of crusts, facets, and surface hoar is buried down close to metre. The likelihood of triggering this layer is decreasing, but the consequences of an avalanche failing on this layer are high.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 5