Avalanche Forecast

Issued: Dec 21st, 2014 7:51AM

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

pgoddard, Avalanche Canada

Purcells.

Have a safe and fun holiday.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

On Monday, expect flurries or light snow with light to moderate NW winds. Freezing levels are expected to gradually drop to near valley floor by Tuesday. A second storm system is due to arrive some time on Tuesday, bringing snow (around 5-10cm).

Avalanche Summary

On Saturday, explosives triggered size 2-2.5 slabs at the northern end of the Purcells. These are suspected to have failed on the lower layer of surface hoar, and in isolated spots stepped down to the early November crust. Smaller slabs were also failing on the most recently buried layer of surface hoar. A size 2.5 naturally-triggered slab was observed at 2600m on an east aspect on Friday.

Snowpack Summary

Recent storm snow sits above two layers of surface hoar in the upper snowpack. The more recent of these sits on a crust below about 2100m, and on settled snow at higher elevations. A hard rain crust with facets from early November is buried over 1 m down and is still reactive to light loads in some locations.

Problems

Storm Slabs

Recent new snow has built up over a touchy layer of buried surface hoar crystals.

Avoid freshly wind loaded features by sticking to ridges and ribs.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

In some parts of the region, large avalanches have been failing on a deeply buried weak layer.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 22nd, 2014 2:00PM