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Avalanche Forecast

Feb 4th, 2016–Feb 5th, 2016
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Northwest Coastal.

Snow, wind, and rising freezing levels will increase the avalanche danger. Deeply buried persistent weak layers may be triggered by the increased load from the storm. Patience and a conservative approach to terrain are recommended.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

20-30 cm overnight with extreme southwest winds and freezing level around 800 metres. Another 10-20 cm during the day on Friday with strong southwest winds and freezing levels around 800 metres. Light snow on Saturday with moderate southerly winds and freezing levels about 500 metres. On Sunday, expect increasing southerly winds, rising freezing levels, and moderate precipitation.

Avalanche Summary

No new avalanches reported from the south of the region. On Wednesday in the north of the region there were skier controlled and remotely triggered avalanches up to size 1.5 in the storm snow or on the rain crust from the late January storm. Conditions are expected to change rapidly overnight with storm slabs developing on all aspects and at all elevations.

Snowpack Summary

In the north of the region there is 20-30 cm of new snow that has been transported into deep windslabs above loose facetted snow in sheltered areas, and stiff old wind effected surfaces in exposed terrain. In the south of the region we have reports of 10-20 cm of new snow that is sitting on a new surface hoar layer that was buried on February 3rd. Wind slabs developed in the lee of southeast winds on Wednesday, and more widespread storm slabs developed on Thursday. The January 9th surface hoar/facet layer is down 70-150 cm in most places, and remains a concern on all aspects and elevations, especially with heavy and/or thin-spot triggers. Around the same depth you may also find a surface hoar/facet interface from around New Years. There continues to be a lot of uncertainty regarding the reactivity and distribution of this destructive persistent avalanche problem. A conservative approach to mountain travel is still required.

Avalanche Problems

Storm Slabs

New storm slabs are expected to develop rapidly with forecast new snow and extreme winds. Storm slabs in motion may step down to the deeply buried persistent weak layer resulting in very large avalanches.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

Persistent Slabs

The likelihood of triggering deeply buried surface hoar layers may have decreased; however, the layer remains touchy in many areas and could surprise with disastrous consequences.
Be careful with low angle slopes that may not normally be a concern.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Be aware of thin areas that may propogate to deeper instabilites.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 6