Avalanche Forecast

Issued: Feb 12th, 2013 8:16AM

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.

pmarshall, Avalanche Canada

Cariboos.

Summary

Confidence

Good

Weather Forecast

Wednesday: Light snow early then a mix of sun and cloud. The freezing level drops to 800 m. Winds are light to moderate from the northwest. Thursday: A mix of sun and cloud. The freezing level is near valley bottom. Winds are light from the northwest. Friday: Mainly cloudy with a chance of light snow. The freezing level could jump as high as 1400 m. Winds are light to moderate from the southwest.

Avalanche Summary

No much activity reported in the last couple days. There was one observed cornice failure that pulled out a size 2.5 slab on the underlying slope. It was reported on Monday but was probably a day or two old.

Snowpack Summary

The snow surface consists of wind slab in exposed lee alpine terrain, sun crust on solar aspects, and surface hoar or facets on shady slopes. Below this up to 40 cm of settled storm snow sits on old wind slabs and recently buried weak layers. The late January surface hoar, sun crust, and/or facet layer is down around 80 cm deep and remains a concern for triggering. Use extra caution on large open slopes, cutblocks and convex rolls at and below treeline where the buried surface hoar may be preserved.Cornices are reported to be large throughout the region. The mid-pack is generally well settled and strong and the average snowpack depth at treeline elevations is near 200 cm.

Problems

Wind Slabs

Wind slabs continue to be a concern on lee slopes and behind terrain features like ridges and ribs. They could be triggered under the weight of a person. Looming cornices may threaten slopes below.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

A persistent weak layer of surface hoar, crusts and/or facets lurks around 80 cm deep. This weakness may be reactive to human triggers and can be difficult to predict.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

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