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Avalanche Forecast

Dec 25th, 2014–Dec 26th, 2014
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: South Columbia.

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.

Confidence

Good

Weather Forecast

A ridge of high pressure is strengthening a predominant northwesterly flow which will invade the Interior regions. This will bring relatively dry cool air. Ridgetop winds will blow light-moderate from the northwest and alpine temperatures will hover near -12. Skies will likely remain cloudy with some sunny periods Friday and Sunday. Light precipitation is expected Saturday.

Avalanche Summary

On Wednesday, several natural avalanches up to size 2 were reported and results up to size 3.5 were seen with the use of explosives. The buried surface hoar layer remains very touchy to skier/ rider triggers and numerous avalanches size 1-2.5 were reported. I don't expect things to improve over the holiday period and suspect this layer is primed for human triggers.

Snowpack Summary

New snow 10-30 cm fell Tuesday night. In some parts of the region the new snow is sitting on a thin breakable rime crust, but most concerning is the thick persistent slab (40-90 cm) which is sitting on a very touchy surface hoar layer buried mid-December. Below 2100 m this slab sits on a thick, solid crust that has been acting as a perfect sliding layer. Persistent slabs will be very touchy to the weight of a skier and rider, especially in wind effected areas where the slab is stiffer. A hard rain crust with facets from early November is buried over 1 m down and is currently unreactive but triggering from shallow rocky, unsupported terrain remains a concern.

Avalanche Problems

Persistent Slabs

A very touchy surface hoar layer is buried by a 40-90 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 to anything.>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 shallow snowpack areas where triggering is more likely.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 3 - 6