Avalanche Forecast

Issued: Feb 11th, 2013 3:00PM

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.

pmarshall, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Timing of incoming weather is uncertain

Weather Forecast

Tuesday: A frontal system approaches the coast and moves across the province. Flurries are expected during the day (2-3 cm) and moderate snow in the evening and overnight (~10 cm). Winds increase to strong from the southwest later in the afternoon. The freezing level is around 1200 m. Wednesday: Possible flurries early then a mix of sun and cloud. The freezing level drops to 500 m. Winds are light from the northwest. Thursday: A mix of sun and cloud. The freezing level is near valley bottom. Winds are light from the west.

Avalanche Summary

A few natural cornice releases were reported in the region on the weekend. The failing cornices did not release slab avalanches. There were also reports of loose snow avalanches up to size 2 on steep solar aspects on Sunday.

Snowpack Summary

The snow surface consists of soft wind slab in exposed 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.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - 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 12th, 2013 2:00PM