Avalanche Forecast

Issued: Jan 15th, 2013 9:31AM

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

pgoddard, Avalanche Canada

Cariboos.

Summary

Confidence

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

Weather Forecast

Wednesday-Friday: North-westerly winds. Freezing level is at valley bottom, with alpine inversions possible (parcels of warm air which could bring alpine temperatures close to 0). Light snow is possible on Wednesday and Friday.

Avalanche Summary

No new avalanches have been reported.

Snowpack Summary

Recent northerly to westerly winds have left new wind slabs behind ridges and terrain breaks at alpine and treeline elevations. A weak interface (surface hoar, a sun crust or facets) buried in early January is of most concern on steep south to south-west aspects and below about 1700 m in sheltered areas. Snowpack test results on this interface vary from sudden to no results. Recent storm snow is fully settled in some locations, and still showing easy to moderate shears in other places. Watch out for rapid warming on alpine slopes over the next couple of days, which could weaken the slab above these interfaces. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack. Check out this YouTube video which demonstrates some of the weak layers and test results found around Valemount BC.

Problems

Wind Slabs

Wind slabs may be found behind terrain breaks such as ridges and ribs. It may be possible for a wind slab to step down to deeper instabilities.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Persistent weaknesses are buried at a prime depth for human triggering. Triggering persistent slabs will become more likely if the snowpack experiences rapid warming.

Avoid thin, rocky or sparsely-treed slopes.>Choose the deepest and strongest snowpack areas on your run.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 6

Valid until: Jan 16th, 2013 2:00PM