Avalanche Forecast

Issued: Dec 19th, 2014 8:30AM

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

Avalanche Canada triley, Avalanche Canada

Avalanche danger rising to HIGH as the storm slab continues to develop.

Summary

Confidence

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

Weather Forecast

Entering a very stormy period for the North Coast. Very strong Southerly winds overnight and during the day on Saturday. 15-25 cm of snow tonight above 600 metres elevation. Another 15-25 cm during the day on Saturday as freezing levels rise up to at least 1000 metres and maybe as high as 1400 metres in some areas. Winds decreasing to strong by Sunday morning with another 10-15 cm expected and a further 10-15 cm during the day. Monday should be drier with Westerly winds and dropping freezing levels.

Avalanche Summary

No new avalanches reported. The forecast new storm is expected to increase avalanche activity over the next few days.

Snowpack Summary

A new storm slab is developing above the recent mix of surfaces which include wind slabs in alpine terrain, hard rain crusts at lower elevations and weak surface hoar crystals. Last week's heavy rain affected southern parts of the region up to alpine elevations, while the far north remained drier and generally has a weaker snowpack. Areas which previously received rain have probably now formed a hard frozen crust. Upper elevation terrain and far northern areas are likely to have wind slabs and large fragile cornices. Deeper in the snowpack, weaknesses such as the mid-November crust-facet layer still exist. Avalanches at this interface have become unlikely, although the consequences of a release remain high. This layer may be more sensitive to triggering in steep, unsupported high alpine terrain, or in the far north of the region.

Problems

Storm Slabs

An icon showing Storm Slabs
Continued new snow should add to the developing storm slab. This slab is expected to consolidate and allow for longer propagations resulting in larger avalanches.
Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.>Avoid freshly wind loaded features.>Cornices may be large and fragile with new growth. Stay well to the windward side of corniced ridges, and avoid travelling beneath cornices.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Dec 20th, 2014 2:00PM

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