Avalanche Forecast

Issued: Jan 18th, 2013 9:17AM

The alpine rating is moderate, 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 - Due to variable snowpack conditions

Weather Forecast

Saturday: Moderate to strong W winds. Alpine temperature near -3. Light snow possible.Sunday: Light to moderate W winds. Alpine temperature near -2. No snow.Monday: Light SW winds. Alpine temperature near -2. No snow.

Avalanche Summary

Several naturally-triggered size 1 wind slabs were observed on Tuesday. A skier also triggered a size 1.5 slab on a north aspect at 1300 m, which failed on buried surface hoar. No avalanches have been reported since then.

Snowpack Summary

Recent strong north to north-westerly winds have left wind slabs in many areas, even at treeline. These are likely to be gaining strength as time goes on and the amount of snow available for transport diminishes. Settled storm snow sits above surface hoar (found especially below treeline in sheltered areas), a sun crust (on steep S to SW -facing slopes) and facets. The distribution of these weaknesses is patchy, but where they exist, it may still be possible to trigger a large avalanche with the weight of a person or snowmobile. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack, which is now considered inactive.

Problems

Wind Slabs

Wind slabs may be found behind terrain breaks such as ridges and ribs.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

Triggering persistent slabs is becoming less likely, but a cautious approach is still advised. Carefully assess steep south-facing slopes and slopes below about 1900 m, where persistent weaknesses are most likely to be lurking.

Dig down to find and test weak layers before committing to a line.>Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 5

Valid until: Jan 19th, 2013 2:00PM