Avalanche Forecast

Issued: Dec 24th, 2014 7:57AM

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

swerner, Avalanche Canada

Purcells.

Tricky avalanche conditions exist out there, use a conservative approach and make good choices. Happy Holidays everyone!

Summary

Confidence

Good

Weather Forecast

By Thursday an upper ridge will build behind the cold front bringing cooler conditions with mostly cloudy skies and light precipitation amounts. Light northwest winds and alpine temperatures dropping to -15 will persist through the forecast period. Freezing levels at valley bottom.

Avalanche Summary

On Tuesday, reports from the field were still indicating that the buried surface hoar layer is very touchy to skier/ rider triggers and numerous avalanches size 1-2.5 were reported. With a thicker slab overlying this touchy layer, I don't expect things to improve over the holiday period and suspect this layer is primed for human triggers.

Snowpack Summary

New snow 10-20 cm fell Tuesday night, with southern locations seeing the higher amounts. Moderate SW winds accompanied the snowfall adding more load to the upper snowpack. This brings storm snow totals 30-80 cm above a very touchy surface hoar layer that was buried mid-December. Below 2100 m this storm slab sits on a thick, solid crust that has been acting as a perfect sliding layer. Storm slabs will be very touchy to the weight of a skier/ rider, especially in wind effected areas. A hard rain crust with facets from early November is buried over 1 m down and may be reactive to light loads in some locations.

Problems

Storm Slabs

A thick storm slabs sits over a predominant surface hoar layer which is very touchy to skier and rider triggers.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

The new snow load continues to build and this could reawaken the Nov 9 layer at the bottom of the snowpack. Shallow avalanches running on the surface hoar may also trigger this layer.

Conditions may be worse in the north of the region, so get to know your local snowpack.>Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Dec 25th, 2014 2:00PM