Avalanche Forecast

Issued: Dec 23rd, 2013 8:25AM

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

esharp, Avalanche Canada

Cariboos.

Summary

Confidence

Poor - Intensity of incoming weather systems is uncertain

Weather Forecast

Synopsis: A return to a drier, colder, northwesterly flow will occur tonight. This is forecast to persist briefly until the next system hits the NW of the province. This system resembles the last with precipitation expected to spill over into the Northern Columbias bringing 10 to 25cm of snow through the forecast period.Tonight and Tuesday: Mainly cloudy with isolated flurries. Freezing levels will remain at valley bottom. Winds will be moderate gusting to strong from the west.Wednesday: Expect light snow through the day and overnight. Ridge winds will be moderate gusting to extreme from the west.Thursday: Light snow will continue with heavier accumulations expected in the north of the region. Freezing levels will rise to 1000m. Winds will be moderate from the southwest.

Avalanche Summary

Explosive control work over the weekend produced a couple of avalanches to size 2.5 on upper elevation N through NE facing slopes that likely failed on the basal facets near the ground.

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 is a mixed bag of soft storm slabs and wind slabs, sitting above a variety of week old surfaces. Previously warm temps and as much as 85cm of snow through December have combined to form a cohesive mid pack on top of the November 28 surface hoar and facets. Snowpack tests are showing this layer pop 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

Storm Slabs

New snow, accompanied by wind has loaded a layer of surface hoar . This has resulted in touchy storm slabs . Dig down to see if the surface hoar is present in your area and keep your terrain selection conservative until you are sure it does not.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>The new snow will require several days to settle and stabilize.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

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. Storm slab avalanches may step down and trigger larger persistent slab avalanches.

Whumpfing is direct evidence of a buried instability.>Be aware of the potential for large, deep avalanches.>Avoid rock outcroppings, steep convexities and anywhere the snowpack feels thinner than average.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Dec 24th, 2013 2:00PM