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Avalanche Forecast

Jan 17th, 2012–Jan 18th, 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
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
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: South Columbia.

Confidence

Fair - Timing of incoming weather is uncertain on Friday

Weather Forecast

Wednesday: Cloudy with a few snowflakes. Cold (around -20C). Moderate to strong westerly winds. Freezing level valley floor.Thursday: Light snow possible at times. Remaining cold. Friday: The next frontal system is due to hit the region late in the day, bringing moderate-heavy snow, rising temperatures and gusty winds. Freezing level climbing near 1500m by the evening.

Avalanche Summary

Recent reports include a few reluctant slope cut size 1 soft slabs on steep, convex, unsupported features. They had limited propagation and did not run far. Low density storm snow is sluffing readily in steep terrain. In some cases they're entraining considerable mass and reaching up to size 2.

Snowpack Summary

5-10cm additional snow brings storm totals to about 40-50cm. This sits over a variety of surfaces (facets, surface hoar in sheltered areas, soft slabs, hard slabs, wind crust, and a melt-freeze crust below treeline). So far the storm snow has remained relatively cohesionless and has only been reacting as a very soft slab in a few areas. However, I'd expect wind slabs to be developing now in open areas.A surface hoar layer buried in mid-December is gaining strength, but professionals are still treating it with caution, as the consequences of an avalanche on this layer would be high. It's now down about 130cm in the snowpack.

Avalanche Problems

Wind Slabs

New wind slabs are lurking below ridgecrests, behind terrain features and in cross-loaded gullies.

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

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

Storm Slabs

Up to 50cm of storm snow is settling slowly into a soft slab in places sheltered from the brunt of the wind. In other sheltered, steep terrain, loose dry sluffing is still a concern. Sluffs can entrain mass and become quite large.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3