Avalanche Forecast

Issued: Jan 11th, 2013 9:08AM

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

pgoddard, Avalanche Canada

Cariboos.

Conditions will be tricky to manage this weekend, as a touchy surface hoar layer is buried only on some slopes and not others. Make constant snowpack assessments as you travel and take a cautious approach to terrain selection.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Saturday: Light W wind. Alpine temperature near -15. Trace of snow.Sunday: Light NW wind. Alpine temperature near -14. No snow.Monday: Light W wind. Alpine temperature near -10. Light snow.

Avalanche Summary

A natural cycle of size 1-2.5 storm slabs occurred over the last few days. Skiers also triggered avalanches up to size 2, failing on buried surface hoar or facets. The touchy nature of the buried surface hoar has been revealed by skier-remote triggered avalanches, and a skier-triggered size 1 which ran across a flat bench and triggered a size 2 on another slope. 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) fell across the region, leaving the buried surface hoar at a prime depth for human-triggering. Recent 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

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.

Be wary of slopes that did not previously avalanche - even on low angle terrain.>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

Expected Size

1 - 5

Wind Slabs

Recent 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.>Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid steep slopes below cornices.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Jan 12th, 2013 2:00PM