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Archived

Avalanche Forecast

Mar 7th, 2014–Mar 8th, 2014
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: Northwest Inland.

Confidence

Fair - Due to the number of field observations

Weather Forecast

Saturday: Cloudy with periods of snow – 5-15 cm. The freezing level is around 1000 m in the north and 1500 m in the south. Winds are moderate to strong from the S-SW. Sunday: Cloudy with flurries. The freezing level is around 1000-1400 m. Winds are moderate to strong from the S-SW. Monday: Mainly cloudy with a chance of flurries and sunny breaks. The freezing level is around 1000 m. Winds are moderate S-SW.

Avalanche Summary

No new avalanche activity has been reported. Expect the likelihood of triggering slab avalanches to increase this weekend.

Snowpack Summary

5-10 cm of dry new snow sits on a layer of surface hoar and/or a thick layer of facetted snow on shady slopes at all elevations. The new snow is likely sitting on a sun crust on steep solar aspects and various wind affected surfaces in exposed terrain. The early February weak layer of facets, crusts, and surface hoar is buried down about 35-80 cm. Cold temperatures have not settled the snow above this weak layer into a cohesive slab, and the cold has preserved the weak layer and associated crusts. This layer could become reactive in the next couple days with additional loading and significantly warmer temperatures. Basal facets and depth hoar remain a concern in areas with thin or variable snow cover.

Avalanche Problems

Wind Slabs

Strong S-SW winds will likely build new dense wind slabs, while old hard wind slabs may be lurking on south and east aspects. A relatively thin wind slab could step down to the deeper mid February persistent weak layer.
Choose well supported terrain without convexities.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

New loading from snow and wind or rising temperatures could create a cohesive slab over this persistent weakness, down around 30-80 cm deep, and increase the odds of triggering this problem.
Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Use conservative route selection, stick to moderate angled terrain with low consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 5