Avalanche Forecast

Issued: Jan 10th, 2013 9:40AM

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

pgoddard, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Friday: Light NW wind. Alpine temperature near -14. No precipitation.Saturday:Light W wind. Alpine temperature near -15. Trace of snow.Sunday: Light W wind. Alpine temperature near -14. No snow.

Avalanche Summary

A natural cycle of size 1-2.5 storm slabs occurred over the last three days. Skiers also triggered avalanches up to size 2, failing on buried surface hoar or facets. The touchy nature of the buried surface hoar was revealed by a skier-remote triggered avalanche, and a skier-triggered size 1 which ran across a flat bench and triggered a size 2 on another slope. Both these events were in the 1350-1450m elevation band on N/NE aspects in the south of the region.

Snowpack Summary

New snow has developed into slabs, with a weak bond to old snow surfaces including surface hoar (found especially below about 1600 m in sheltered areas) and facets. Variable amounts of storm snow (25-90 cm) have fallen across the region, meaning the avalanche danger is likely to be different from place to place. In heaviest-affected areas, there is the potential for deep and destructive storm snow avalanches. Strong winds have left wind slabs in the lee of terrain breaks such as ridges and ribs at alpine and treeline elevations. In areas sheltered from the wind, fast-moving sluff could throw you off your feet or carry you into a terrain trap. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack.

Problems

Wind Slabs

Strong winds have shifted snow into wind slabs which could fail with the additional weight of a person or snowmobile.

Be cautious as you transition into wind affected terrain.>Travel on ridgetops to avoid wind slabs on slopes below.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 5

Persistent Slabs

Storm snow is particularly reactive where it overlies buried surface hoar. This weakness may be triggered easily, or even from a distance. Avalanches could be surprisingly large.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Remote triggering is a concern, watch out for adjacent slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 5

Valid until: Jan 11th, 2013 2:00PM