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Archived

Avalanche Forecast

Mar 30th, 2012–Mar 31st, 2012
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
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
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: Kootenay Boundary.

If more snow falls than forecasted (>15cm), the danger may be HIGH. Be locally aware of conditions.

Confidence

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

Weather Forecast

Saturday: A system south of the border will send moderate precipitation into the region, accompanied by moderate southwesterlies. 15cm is possible. Freezing levels could climb to 1500m. Sunday / Monday: A series of lows will push precipitation into the region with continued southerly flow and freezing levels reaching 1200m.

Avalanche Summary

Natural, explosive and human triggered avalanches have been reported up to size 2.0 failing on the March 26 interface. At lower elevations (where the surface is moist) these are running as loose events and at higher elevations the new snow is propagating as a slab.There was one sympathetic triggered avalanche that release on the early February weakness 150cm deep.

Snowpack Summary

30-50cm of new snow now overlies the March 26 interface. This has been accompanied by consistently moderate and at times gusty southwesterly winds forming windslabs in lee locations. Cornices loom, and will continue to grow with this weather pattern. The March 26 interface is a crust on all aspects except true north treeline and alpine, where small surface hoar (5mm) is present in sheltered places. The bond between the new snow and this interface is weak, especially where the surface hoar is present. At lower elevations (1600m and below), the high freezing levels have made the new snow heavy and moist. The deep, persistent early February surface hoar lingers in the snowpack giving sudden results in testing. Concern remains with heavy triggers and rapid loading.

Avalanche Problems

Wind Slabs

The increased wind and new snow are forming windslabs in lee zones at ridgecrest. These overlie a slick melt freeze crust in most locations and surface hoar on North aspects. A small windslab event could step down to the deep, persistent weakness.

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

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 4

Storm Slabs

The new snow is bonding poorly to the March 26 interface. At lower elevations, expect moist sluffing, while higher up (drier snow) the storm slab is more cohesive. A small storm slab event (or sluff) could step down to the deep weaknesses.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 4

Cornices

Cornices are very large and will grow under the current conditions. There is potential for triggering deep persistent slabs on underlying slopes.

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

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 2 - 7