Avalanche Forecast

Issued: Dec 22nd, 2013 8:59AM

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

ghelgeson, Avalanche Canada

Cariboos.

These danger ratings are based on forecasted snow amounts of 10 - 15 cm. If actual amounts exceed 15 cm, the danger rating will be high in the Alpine and at Treeline.

Summary

Confidence

Poor - Intensity of incoming weather systems is uncertain on Monday

Weather Forecast

Synopsis: The region will see a one/ two punch of warm then cold air Sunday night into Monday. The result is a rising freezing level and a small amount of snow for the Cariboos. Sunday Night: Dropping to around 800m overnight. Precip: 5/10mm - 10/15cm Monday: Freezing Level: 1100m Precip: Nil Wind: Mod, gusting Strong WTuesday: Freezing Level: 600m Precip: Nil Wind: Mod, W gusting Extreme.Wednesday: Freezing Level: 1100m Precip: Trace Wind: Mod, gusting Strong South

Avalanche Summary

Explosive control work Saturday 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 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

Storm Slabs

New snow, wind and surface hoar are colliding Monday. This will likely result in a very touchy storm and wind slab problem. Dig down to see if the surface hoar is present in your area and keep your terrain selection conservative.

The new snow will require several days to settle and stabilize.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

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

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Choose conservative well supported lines and watch for clues of instability.>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 23rd, 2013 2:00PM