Archived

Avalanche Forecast

Dec 9th, 2014–Dec 10th, 2014

Alpine

4: High

The avalanche danger rating in the alpine will be high

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

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

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Coastal.

Heavy loading from snow, wind, and rain is likely resulting in natural avalanche activity.

Confidence

Fair - Due to the number of field observations

Weather Forecast

On Wednesday expect another 5-15 mm of rain (or cm of snow) as freezing levels to drop as low as 1500 m in the southern part of the region or lower up north, and alpine winds continue to blow strong from the southeast. Thursday is looking mostly dry as freesing levels hover around the 1000-1500 m mark and alpine winds ease off throughout the day. A bit more snow could arrive on Friday with up to 10 cm in some areas accompanies by moderate to strong southwesterly alpine winds and freezing levels dropping below 1000 m.

Avalanche Summary

Reports from Monday include several explosive-triggered storm and wind slab avalanche up to Size 2.5 at all elevations and on all aspects. The slabs were no deeper than 35 cm and failed on old facets under recent storm snow, or right on the ground in shallow snowpack areas below treeline.

Snowpack Summary

Heavy rain is saturating the upper snowpack and resulting in wet, loose, and cohesionless surface snow as high as alpine elevations in the southern part of the region. While in the alpine and as low as treeline elevations further north wet snow and wind has formed new storm slabs and is overloading previous weaknesses buried within the snowpack, such as the mid-November crust-facet layer.

Avalanche Problems

Storm Slabs

Heavy storm snow is expected to bond poorly and overload deeper weaknesses in the snowpack. Extreme southerly winds could also create dense wind slabs well below ridge tops.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 5

Loose Wet

Expect heavy loose wet sluffs in steep open terrain and in gullies.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2