Avalanche Forecast

Issued: Dec 21st, 2013 9:12AM

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.

ghelgeson, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Sunday

Weather Forecast

Synopsis: The pattern switches to a more characteristic SW flow over the next 24 hours which will open the door to some decent snow accumulations. Freezing levels rise to around 1000m, but the upper elevations should do quite well with regard to snowfall.Sunday: Freezing Level: 700m; Precip: 4/8mm - 8/15cm Wind: Lht gusting Strong SouthSunday Night: Freezing Level: Rising to 1000m Precip: 13/18mm - 20/30cm Monday: Freezing Level: 1200m Precip: 2/4mm - 4/8cm Wind: Mod/Strong, W Tuesday: Freezing Level: Valley Bottom Precip: Nil Wind: Lht SW

Avalanche Summary

A few natural size 2 avalanches were observed Friday on a north facing slope with a shallow snowpack.

Snowpack Summary

Snowpack depths at Treeline are between 75 - 120cm. Alpine depths vary between 100 - 180cm. We're dealing with a complex snowpack in the Cariboo Mountains at this time. See this video for a great visual.The upper snowpack contains storm snow, wind slabs, surface hoar, and facets. Previously warm temps and as much as 85cm of new snow have combined to form a cohesive slab on top of the November 28 surface hoar and facets. Snowpack tests are showing Sudden Planar results on this layer with medium loads which indicates the potential for human triggering. There's not a whole lot of snow between riders and sugary snow (facets) near the base of the snowpack. In some places this crust facet combo is failing naturally. As a result you'll notice that there is a Persistent Slab problem on the front page. Human triggering of large destructive avalanches is possible at this time.

Problems

Wind Slabs

Moderate winds and fresh snow continue to come together to create fresh wind slabs. These new wind slabs are forming on the backs of old wind slabs that may still be sensitive to human triggering.

Avoid freshly wind loaded features.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Persistent Slabs

A buried persistent weak layer of facets, surface hoar, and/or crust is buried by 40-70 cm of storm snow and may be susceptible to human triggering. Wind slab avalanches may step down and trigger larger persistent slab avalanches.

Avoid rock outcroppings, steep convexities and anywhere the snowpack feels thinner than average.>Choose conservative well supported lines and watch for clues of instability.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Dec 22nd, 2013 2:00PM