Avalanche Forecast

Issued: Dec 10th, 2014 8:07AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Loose Wet.

ccampbell, Avalanche Canada

Northwest Coastal.

Recent storm snow will likely take a few days to gain strength.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Another 5-10 cm of snow is expected for Thursday as freezing levels drop to 1200 m and alpine winds ease off to moderate but gusty southerlies. A brief drying ad clearing trend is expected overnight Thursday before another 5-10 cm falls on Friday with freezing levels down to 500 m and moderate southwesterly alpine winds. Unsettled weather is expected for Saturday with some sunny breaks in the afternoon and isolated light flurries. Freezing levels should remain at 500 m with light to moderate alpine winds.

Avalanche Summary

Reports from Tuesday include explosive-triggered 10-35cm thick storm and wind slab avalanche up to Size 2.0 at all elevations and on all aspects. Many natural wet loose avalanches up to Size 2.5 were also observed at lower elevations, some entraining the entire snowpack to the ground.

Snowpack Summary

Heavy rain has saturated the upper snowpack and 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 should soon 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 50 cm of recent snow and wind has formed new storm slabs and overloaded previous weaknesses buried within the snowpack, such as the mid-November crust-facet layer.

Problems

Storm Slabs

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

Expect conditions to deteriorate. Assess conditions continually as you travel and be prepared to change plans.>Be cautious as you transition into wind affected terrain and avoid wind loaded slopes near ridge crests.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Loose Wet

Slushy cohesionless snow at lower elevations will likely remain senssitive to human triggers until temperatures drop. Especially in steep cliffy areas and gullies.

Be aware of party members below you that may be exposed to your sluffs.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Dec 11th, 2014 2:00PM