Avalanche Forecast

Issued: Apr 20th, 2012 10:20AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs, Loose Wet and Wet Slabs.

pgoddard, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Saturday: Cloudy with scattered light precipitation possible. Light to moderate southerly winds. Freezing level around 1500 m.Sunday: Mainly dry and sunny. Freezing level around 1200 m, falling to near valley floor overnight. Light winds.Monday: Light, scattered precipitation. Freezing level rising to around 1000 m in the afternoon. Light winds.

Avalanche Summary

Reports of natural glide activity from the Skeena corridor continue. Cornice fall and ice fall triggered 1-1.5 m deep wet slabs in the Bear Pass area on Thursday.

Snowpack Summary

New wind slabs may have built on lee slopes. The snow surface below about 1000 m has not been re-freezing overnight, leading to weak soft snow. Large cornices and ice cliffs pose a threat from above.As we transition into spring, the surface layers have a great deal of influence on the snowpack. When there is a solid re-frozen surface crust, travel is fast and easy, and the snowpack is held together by the surface cap. Any deeper persistent weak layers are unlikely to fail until the surface cap breaks down from daytime heating. When there is no crust, surface layers and any deeper weak layers may fail, depending on the amount of heat and the triggering force that is applied. If it cools off and snows, new snow and wind slabs may not bond well to the hard spring crusts. For more information on Spring Conditions and ways to mitigate risk, please visit the new Forecasters' Blog Post.

Problems

Wind Slabs

New wind slabs may have developed with recent snow and wind. Watch for these behind ridges and terrain breaks.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Loose Wet

Loose wet avalanches are most likely during periods of warming from rainfall or sunshine. These can push you around, entrain mass and become surprisingly large.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 5

Wet Slabs

Warm temperatures or rain may continue to weaken the snowpack, leading to full-depth releases. Avoid traveling on or underneath any slopes which sport glide cracks. Large glide slabs have been releasing all week in specific terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 7

Valid until: Apr 21st, 2012 9:00AM