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Archived

Avalanche Forecast

Dec 21st, 2013–Dec 22nd, 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
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: Glacier.

Weather Forecast

Isolated flurries are forecast today, with freezing levels remaining at valley bottom and light to moderate NW ridge top winds.  A pacific frontal system is forecast to bring light, possibly moderate snow starting tonight and continuing into Monday.  Freezing levels are forecast to rise to 1000m on Monday.

Snowpack Summary

Up to 80cm of snow has settled over surface hoar at lower elevations, mixed forms and variable wind slabs at higher elevations. This interface failing sudden planar in snowpack tests. Strong winds have formed wind slabs and wind loaded pockets at treeline and above. At the base of the snowpack 2 persistent weak layers are surrounded by mixed forms.

Avalanche Summary

Natural avalanche activity has tapered off, but slabs now sit at depths easily triggered by light-loads, like humanoids. A number of field crews in the Pass yesterday backed off of larger slopes due to the ease in which the slabs were reacting down 70-80cm.

Confidence

Intensity of incoming weather systems is uncertain on Monday

Avalanche Problems

Wind Slabs

Firm, wind deposited snow has formed slabs in exposed terrain.  Use caution in lee areas at treeline and above. 
Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Persistent Slabs

A weak layer is buried down around 80 cm.  If triggered, a large, high consequence avalanche will result. Carefully evaluate big terrain features by digging and testing adjacent, safe slopes.
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 - 4