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Avalanche Forecast

Jan 11th, 2013–Jan 12th, 2013
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
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

Regions: Sea To Sky.

Confidence

Good

Weather Forecast

Saturday: A mix of sun and cloud with a chance of flurries close to the coast. Freezing level is at valley bottom with alpine temperatures around -10. Winds are light from the north-northwest. Sunday: A mix of sun and cloud. Freezing level remains at valley bottom. Winds are light to moderate from the north. Monday: A mix of sun and cloud. Alpine temperatures should rise during the day with an above freezing layer developing. Winds are moderate from the north. 

Avalanche Summary

There are a few reports of accidentally triggered slab avalanches up to size 2 on Thursday. A widespread natural avalanche cycle was observed on Wednesday with numerous slab avalanches up to size 2 and a few larger events up to size 3.

Snowpack Summary

A dusting of up to 15 cm of new  snow sits on the 40-60 cm of snow that fell earlier this week. Northerly outflow winds have created thin new wind slabs in exposed terrain, while older wind slabs still exist from the previous storm. Below the storm snow is a weak layer of surface hoar, facetted snow, and/or a crust. Snowpack tests on Wednesday continued to yield easy to moderate sudden planar, or "pops", results on this interface. No significant weaknesses have been reported recently below this in the mid snowpack layers. Near the base of the snowpack, a crust/facet layer exists, which is now unlikely to be triggered, except perhaps by heavy triggers in steep, shallow, rocky terrain where more facetting has taken place.

Avalanche Problems

Persistent Slabs

It may be possible to trigger avalanches that release on a weak layer of surface hoar or facetted snow down 50-70 cm.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Choose conservative lines and watch for clues of instability.>Be wary of slopes that did not previously avalanche - even on low angle terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 5

Wind Slabs

Northerly winds have created thin pockets of wind slabs in lee and cross-loaded terrain features, while older buried wind slabs exist on exposed north facing slopes.
Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3