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Archived

Avalanche Forecast

Feb 1st, 2012–Feb 2nd, 2012
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
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
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

Good - -1

Weather Forecast

Thursday: Heavy precipitation with up to 60mm expected. Extreme southerly winds and freezing levels as high as 1200m. Friday and Saturday: Light to moderate precipitation continues throughout the period, with some breaks, all in a moderate southwest flow.

Avalanche Summary

Warm temperatures and light to moderate precipitation resulted in several low-elevation natural storm slab avalanches up to Size 2. Explosive control on Tuesday produced numerous 40-60cm thick wind slab avalanches up to Size 2.5 with wide propagation on all aspects in the alpine. Several 100-150cm thick slab avalanches up to Size 3.5 were also triggered.

Snowpack Summary

Total snowpack depths are at new record levels for this time of year. Recent warm temperatures helped settle storm snow into a touchy surface slab at lower elevations. Other weaknesses within and under (Jan. 20th facets) the 150+cm of recent storm snow create the potential for step-down avalanches, but things seem to be settling rapidly. Strong winds associated with recent storms means large weak wind slabs and cornices on lee and cross-loaded terrain. Most snowpack concerns are limited to the surface layers, however large triggers such as cornice falls and smaller avalanche stepping-down could affect deeper weaknesses.

Avalanche Problems

Wind Slabs

Widespread due to strong, shifting winds and large amounts of snow available for transport, but are generally lurking below ridgecrests, behind terrain features and in cross-loaded gullies. They can fail as very large, destructive avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 2 - 7

Storm Slabs

Large storm slab avalanches have been occurring for the past week and are expected to continue with heavy loading from rain, snow, and wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 2 - 6