Avalanche Forecast

Issued: Jan 17th, 2013 8:49AM

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 - Due to variable snowpack conditions

Weather Forecast

Friday: Moderate to strong NW winds. Alpine temperature near -4. No snow.Saturday: Moderate to strong W winds. Alpine temperature near -3. No snow.Sunday: Light to moderate W winds. Alpine temperature near -3. 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.

Snowpack Summary

Strong north to north-westerly winds have left wind slabs in many areas, even at treeline. 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. It may be possible for a wind slab to step down to deeper instabilities.

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

Likely

Expected Size

1 - 4

Persistent Slabs

Triggering persistent slabs is most likely on south-facing slopes and in sheltered terrain below treeline.

Assess open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Be wary of steep southerly aspects, where a buried crust may be most reactive.>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 18th, 2013 2:00PM