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Avalanche Forecast

Jan 12th, 2013–Jan 13th, 2013
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
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
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
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

Regions: Northwest Coastal.

Confidence

Good

Weather Forecast

Sunday: Mainly cloudy with sunny breaks and a chance of flurries. Temperatures should remain cool during the day but an above freezing layer (AFL) is expected to develop late in the day. Winds are moderate to strong from the northwest.Monday: Mainly sunny. The AFL strengthens with alpine temperatures expected to reach +5. Winds remain strong from the northwest.  Tuesday: Mainly cloudy with a chance of precipitation. The AFL should dissipate but the freezing level remains relatively high at 1600-1800 m. Winds remain strong from the northwest.  

Avalanche Summary

There are no new natural avalanche reports. Explosive control work near highway corridors over the past couple days produced several avalanches up to size 3.5. Some of these slides released on the late December surface hoar or facet layer and propagated widely.

Snowpack Summary

Northerly outflow winds have produced new wind slabs in exposed lee and cross-loaded terrain. 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. Recent snowpack tests give generally moderate sudden planar, or "pops", results on this buried surface hoar layer and indicate potential for wide propagation. Near the base of the snowpack, a crust/facet layer continues to concern local avalanche professionals. 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

Persistent Slabs

A weak layer of surface hoar and/or facetted snow exists under the recent storm snow and has been susceptible to human triggering.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 5

Wind Slabs

Northerly outflow winds have created new wind slabs in exposed lee and cross-loaded terrain.
Avoid freshly wind loaded features.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3