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Archived

Avalanche Forecast

Dec 8th, 2012–Dec 9th, 2012
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
1: Low
The avalanche danger rating below treeline will be low
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
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 Inland.

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

Sunday: Light to moderate precipitation throughout the day with strong gusting to extreme northwesterly winds. Alpine temperatures -4 degrees. Monday: Moderate precipitation with strong southwesterly winds. Freezing levels expected at 700m with alpine temperatures -4 degrees.Tuesday: Light precipitation, temperatures cooling to -9 in the alpine. Winds southwesterly moderate to strong.

Avalanche Summary

There is no new avalanche activity to report at this time. 

Snowpack Summary

Wind slab instabilities exist in the upper snowpack at treeline and in the alpine. Treeline snow depths range between 90-125 cm. Snow depths in the alpine are highly variable with deep wind drifts and heavily scoured slopes in exposed areas. A layer of small surface hoar crystals exists at tree-line in isolated sheltered areas. This is most likely buried down 15-20 cm under recent storm snow. A weak layer of facets sitting on a crust exists near the base of the snowpack down 80-130 cm. Test results on this layer earlier this week produced hard, sudden results.

Avalanche Problems

Wind Slabs

New snow and strong west and northwesterly winds have created windslabs in the lee of terrain features. Strong winds often create slabs that extend further down the slope than expected and in open areas below treeline.
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.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4

Deep Persistent Slabs

Deeply buried facet/crust weaknesses are often prone to remote triggering and step down avalanches. Typical trigger points include thin rocky areas. They may be difficult to trigger, but deep persistent slab avalanches are often very large.
Carefully evaluate and use caution around thin snowpack areas.>Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 6