Archived

Avalanche Forecast

Dec 11th, 2014–Dec 12th, 2014

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

1: Low

The avalanche danger rating below treeline will be low

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

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Coastal.

A gradual improvement in avalanche danger is expected over the weekend.

Confidence

Fair - Due to the number of field observations

Weather Forecast

Expect a change to cooler conditions on Friday and through the weekend. Light to locally moderate snowfall is expected on Friday, tapering off on Saturday. Winds remain light to moderate from the south-west.

Avalanche Summary

A naturally triggered avalanche cycle was observed on Tuesday and Wednesday. At low elevations, many of these were wet and dug deep, failing to ground, up to size 2.5. At treeline and above, storm slabs and wind slabs were reported. In the north, large explosives triggered slabs up to size 3 failing on the November crust layer, with wide propagations at alpine elevations.

Snowpack Summary

Heavy rain which recently saturated the upper snowpack resulted in wet, loose, and cohesionless surface snow as high as alpine elevations in the southern part of the region. As freezing levels drop, this may freeze into a solid surface crust with fresh wet snow stuck on top, depending on elevation. Meanwhile in the high alpine and as low as treeline elevations further north, as much as 70 cm of recent snow and wind has formed new storm slabs. These have overloaded previous weaknesses buried within the snowpack, such as the mid-November crust-facet layer.

Avalanche Problems

Storm Slabs

Recent storm snow may bond poorly and could overload deeper weaknesses in the snowpack. Extreme southerly to easterly winds also created particularly deep and weak wind slabs on leeward slopes well below ridge tops.

Be cautious as you transition into wind affected terrain and avoid wind loaded slopes near ridge crests.>Give the new snow a couple of days to settle and stabilize before venturing into exposed terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 5