Avalanche Forecast

Issued: Dec 8th, 2012 9:14AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Deep Persistent Slabs.

mbender, Avalanche Canada

Northwest Inland.

Summary

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.

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

Valid until: Dec 9th, 2012 2:00PM