Avalanche Forecast

Issued: Dec 30th, 2011 10:17AM

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

ghelgeson, Avalanche Canada

Cariboos.

Summary

Confidence

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

Weather Forecast

One last pulse out of the recent active weather system will affect the region Friday evening before a strong ridge of high pressure anchors itself over Eastern BC for the weekend. Skies clear and cooler temperatures pervade under the ridge which will bring freezing levels down to valley bottom. On Saturday you can expect moderate winds out of the W and a daytime high of -9 with overnight lows dropping slightly to -12. A weakening system slides into the region Monday bringing light precipitation and cloudy skies.

Avalanche Summary

Numerous avalanches from size 1 - 2 have been observed at all 3 elevation bands (BTL, TL, ALP), with failures occurring within the recent storm snow. Interesting to note that a size 3 was observed below treeline in the region yesterday, I suspect the mid December Surface Hoar was to blame.

Snowpack Summary

70-100 cm of total storm snow has fallen since Christmas. Winds have redistributed the storm snow into wind slabs that are widespread in the alpine. Wind slabs can also be found in wind exposed areas at and below treeline. The mid December surface hoar/facet/crust interface is buried anywhere from 80-100cm deep and remains a concern for backcountry users. Avalanche activity on this layer has slowed, but it remains a concern as incremental loading gradually adds more weight to this weak layer. Slopes that have not avalanched in the last week are of particular concern for this persistent weakness. The mid-pack is generally strong and well settled.

Problems

Wind Slabs

Big winds combined with plenty of snow available for transportation have resulted in widespread wind slabs on lee slopes.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Storm Slabs

The region has seen 100 cm since Christmas with another 5 - 10 cm on tap for Friday evening. An avalanche originating in the storm snow could step down and trigger a persistent slab avalanche.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

A surface hoar layer buried approximately a meter below the snow surface is capable of producing large & likely un-survivable avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 6

Valid until: Dec 31st, 2011 8:00AM