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Archived

Avalanche Forecast

Jan 14th, 2013–Jan 15th, 2013
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: Northwest Coastal.

Confidence

Fair

Weather Forecast

Tuesday: Mainly cloudy with a chance of flurries and/or freezing drizzle. An above freezing layer (AFL) is likely between 1000 and 2000 m. Winds are strong from the west.Wednesday: Light snow – 5-10 cm. The freezing level returns to 600-800 m. Winds to strong from the west. Thursday: Light to moderate snow – 10 cm. The freezing level is around 1000 m. Winds are strong from the southwest.

Avalanche Summary

On Sunday there was a report of a size 1.5 skier triggered avalanche on a steep unsupported convex roll on a northerly aspect. This event likely released on the late December surface hoar layer approximately 60 cm deep. There are also a few reports of glide releases in steep south facing terrain.

Snowpack Summary

The snow surface has probably changed from facetted snow and/or surface hoar to a dusting of new snow, a rain or freezing rain crust, and new dense wind slabs depending on aspect and elevation. Below this 60-90 cm of storm snow from last week continues to settle and gain strength. However, a weak layer of surface hoar or facetted snow sits at the base of the storm snow and continues to react in snowpack tests and slope tests. Near the base of the snowpack, a crust/facet layer continues to concern local avalanche professionals. This seems most prevalent near Bear Pass where the snowpack distribution is quite variable. This weakness is unlikely to be triggered by a single person, but it remains possible with a very heavy load (e.g. cornice fall) or from a thin-spot trigger point.

Avalanche Problems

Wind Slabs

Strong northwesterly winds have created new wind slabs in exposed lee and cross-loaded terrain.
Be cautious as you transition into wind affected terrain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3

Persistent Slabs

Warm temperatures will increase the likelihood of triggering the late December persistent weakness, down 60-90 cm.
Choose well supported terrain without convexities.>Watch for wet loose or slab activity with forecast rain and/or warm temperatures.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 5