Avalanche Forecast

Issued: Dec 19th, 2015 8:57AM

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

jlammers, Avalanche Canada

Cariboos.

New snow and extreme ridgetop winds will keep the Avalanche Danger elevated over the next few days.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Sunday

Weather Forecast

Between 10 and 20cm of new snow and strong to extreme southwest ridgetop winds are expected on Sunday. Continued light flurries and moderate southwest winds will persist for Monday and Tuesday. Freezing levels should sit at valley bottom for all 3 days. For a more detailed weather overview, check out our Mountain Weather Forecast at avalanche.ca/weather.

Avalanche Summary

There have been no recent reports of avalanche activity. This may speak more to a lack of observations rather than actual conditions. Wind and new snow will likely be the driver for wind slab avalanche activity over the next few days.

Snowpack Summary

Steady snowfall over the past few days and moderate southwest winds have formed fresh wind slabs in exposed lee features in the alpine and at treeline. Between 80 and 150cm below the surface you'll likely find a weak layer of well-developed surface hoar. This layer is most widespread and reactive at lower elevations (between 1400m and 1800m.) Snow pit tests suggest that human triggering of this interface is still possible, although unlikely. That said, if it does fail the overlying slab is stiff enough to propagate over a wide distance. Below this layer, the snowpack is thought to be generally strong and well-settled.

Problems

Wind Slabs

Continued snowfall and extreme southwest winds will create reactive new wind slabs in the alpine and at treeline. Watch for triggering in the lee of ridge crests, over convexities and in gullies.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Persistent Slabs

A layer of buried surface hoar can be found between 1400m and 1800m. Use increased caution on steep roles in cut blocks and in open glades below treeline.

Avoid open slopes, convex rolls, burns, cutblocks and terrain traps when traveling below treeline. >

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 20th, 2015 2:00PM