Avalanche Forecast

Issued: Feb 5th, 2016 8:03AM

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

triley, Avalanche Canada

Northwest Coastal.

Stormy conditions are elevating the avalanche danger to HIGH. Strong winds and heavy precipitation are developing new storm slabs, and deeply buried weak layers are still a concern for very large avalanches.

Summary

Confidence

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

Weather Forecast

15-20 cm of snow above about 700 metres overnight with winds becoming moderate westerly. 5-10 cm of snow above 500 metres during the day on Saturday with moderate westerly winds. Heavy precipitation, strong southerly winds and freezing levels rising up to 1500 metres on Sunday. Continued heavy precipitation, strong winds, and high freezing levels on Monday.

Avalanche Summary

No new avalanches reported. Suspect that a natural storm snow cycle occurred today in the alpine and at treeline with heavy loading from strong winds, new snow, and rain below 800 metres.

Snowpack Summary

New storm slabs developed on Friday due to strong southwest winds and heavy precipitation. Before the new storm, in the north of the region there was 20-30 cm of recent snow that had 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 had reports of 10-20 cm of recent snow that was 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.

Problems

Storm Slabs

Strong southwest winds and heavy precipitation continue to develop new storm slabs above 700 metres.

Be cautious as you transition into wind affected terrain.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

Storm slabs in motion may step down to deeply buried persistent weak layers resulting in very large avalanches with wide propagations.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Be careful with low angle slopes that may not normally be a concern.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 6

Loose Wet

Rain below 800 metres is soaking the snowpack. Expect loose wet snow to release naturally from steep terrain like cliff bands and gullies.

Stick to non-avalanche terrain or small features with limited consequence.>Stick to simple terrain and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Feb 6th, 2016 2:00PM