Avalanche Forecast

Issued: Jan 12th, 2013 9:00AM

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

pgoddard, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Freezing levels are uncertain for the entire period

Weather Forecast

Sunday: Light NW wind. Alpine temperature near -13, warming overnight. No snow.Monday: Moderate NW wind. Alpine temperature near -3. Light snow.Tuesday: Light to moderate W wind. Alpine temperature near -5. No snow.

Avalanche Summary

A natural and human-triggered cycle of size 1-2.5 storm slabs occurred last week. The touchy nature of the buried surface hoar was 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. Avalanche activity has now decreased, but human-triggering remains a concern.

Snowpack Summary

Recent storm snow is slowly settling above old snow surfaces including surface hoar (found especially below about 1600 m in sheltered areas) and facets. Where it exists, the buried surface hoar is 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 from a distance and avalanches could be surprisingly large.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Be wary of slopes that did not previously avalanche - even on low angle terrain.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 6

Wind Slabs

Wind slabs have formed behind terrain breaks such as ridges and ribs. These could be triggered by the 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.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Jan 13th, 2013 2:00PM