Avalanche Forecast

Issued: Dec 25th, 2014 7:42AM

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

swerner, Avalanche Canada

Cariboos.

Conservative decision making and terrain use is the name of the game when these tricky avalanche conditions persist. Check out the new Forecaster Blog @ avalanche.ca.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Yet another arctic outbreak is approaching, which seems to be the theme this winter. A ridge of high pressure off-shore is strengthening a predominant northwesterly flow. This will bring relatively dry and cool air. Ridgetop winds will blow light-moderate from the northwest and alpine temperatures will hover near -13. Skies will likely remain cloudy with some sunny periods Friday and Sunday. Light precipitation is expected Saturday.

Avalanche Summary

No new avalanches have been reported. On Wednesday, several natural avalanches up to size 2 were reported from the regions to the south and results up to size 3.5 were seen with the use of explosives. The amount of human triggering has lowered but I seem to think it's just a lack of actual reports and not the real story. The buried surface hoar layer remains touchy to skier and rider triggers and I don't expect things to improve over the holiday period.

Snowpack Summary

New snow up to 10 cm fell Tuesday night with light- moderate southwest winds adding more load to the upper snowpack. This brings storm snow totals 40-80 cm above a very touchy surface hoar layer that was buried mid-December. Below 2100 m this persistent slab sits on a thick, solid crust that has been acting as a perfect sliding layer. Persistent slabs remain touchy to the weight of a skier and rider, especially in wind effected areas. A hard rain crust with facets from early November is buried over 1 m down and is currently unreactive, however; triggering from shallow rocky and unsupported terrain remains a concern.

Problems

Persistent Slabs

A very touchy surface hoar layer is buried by a 40-80 cm thick persistent slab. This layer is widespread, and is easily triggered by skiers and riders. Remote triggering with wide propagation is a concern.

Use conservative route selection, dig down and test weak layers before committing.>Stick to simple terrain, small features with limited consequence and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Deep Persistent Slabs

A hard rain crust buried 1-1.5 m down seems to be unreactive, however; likely trigger spots are thin rocky and unsupported terrain, or from shallow snowpack areas.

Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Dec 26th, 2014 2:00PM