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Archived

Avalanche Forecast

Feb 16th, 2013–Feb 17th, 2013
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
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.

Confidence

Fair

Weather Forecast

Sunday:  Freezing Level: 500m, Wind: Mod SW, No significant precip.Monday:  Freezing Level: 500m, rising to 750m Wind: Mod S, No significant precip.Tuesday: Freezing Level: 500m, Wind: Light W, No significant precip.

Avalanche Summary

Avalanche activity on Friday was extensive.  Below treeline both loose and slab avalanches were reported on all aspects. Natural avalanches to size 3.5 were observed in the treeline and alpine elevations as storm snow failed and ran full path.  Sizes were slightly diminished in the south of the region, but still significant as many isolated terrain features failed resulting in both loose and slab avalanches to size 2.

Snowpack Summary

The latest system favored the North where up to 70cm fell as of Friday evening.  Southern accumulations dim in comparison coming in around 10cm.  As a result, I've weighted northern observations a bit heavier in my analysis.  Moderate to Strong winds were initially out of the SW, switching to NW during the later half of the storm creating stiff and deep wind slabs at treeline and in the alpine.  Lower elevation slopes received rain and warm temperatures which left many below treeline slopes saturated. The new snow overlies heavy accumulations from earlier in the week that have most likely gained considerable strength. I would imagine that with the ongoing weather pattern, significant cornice development has also taken place.The mid and lower snowpack layers are generally well settled.

Avalanche Problems

Storm Slabs

Storm slabs at upper elevation range in depth from 30 cm in the south to a meter plus in the north. 
Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>Extra caution needed around cornices with current conditions.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 6

Loose Wet

Slopes below 500m are unlikely to refreeze overnight.  Watch for slow-moving wet loose avalanche activity and be sure you know what's above you as you travel through low elevation terrain. 
Watch for loose avalanche activity on low elevation slopes that have grown sloppy with the recent rain and warm temps.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 3