Avalanche Forecast

Issued: Dec 28th, 2014 7:28AM

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

triley, Avalanche Canada

Purcells.

Avalanche danger is expected to remain at Considerable during the forecast cold and clear weather for the end of the year.

Summary

Confidence

Fair

Weather Forecast

Gradually clearing overnight with light Northeast winds and alpine temperatures dropping down to about -22. Mostly clear and cold on Monday with light to moderate Northeast winds and alpine high temperatures around -20. Clear and cold on Tuesday with light Northwest winds. Continued clear and cold on Wednesday.

Avalanche Summary

No natural avalanches reported. Explosives control work resulted in avalanches up to size 1.5 that appear to have run on the mid-December surface hoar that is buried down 40-60 cm.

Snowpack Summary

Some areas may have a thin layer of surface hoar that was buried on December 27th and now has about 5-10 cm of light dry snow above. The slab above the persistent weak layer of surface hoar and crust that was buried in mid-December is now 40-60 cm thick and gives mostly sudden planar results in snow profile tests when moderate forces are applied. The persistent slab problem is widespread across the region and is not expected to improve it's bonding properties during the forecast dry and cold weather. Shallow snowpack areas continue to have concerns for a deeper early season crust/facet layer down more than a metre that may collapse under large loads or from weak trigger spots around exposed rocks and/or trees.

Problems

Persistent Slabs

Thin windslabs and recent storm slabs may be sitting on a weak layer of surface hoar and/or a crust. This problem may persist through the Holiday season.

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

Shallow snowpack areas may continue to have concerns for deeply buried crusts with facets at the interface. Large triggers like storm slab avalanches in motion may step down to near the ground where this problem exists.

Be aware of thin areas that may propogate to deeper instabilites.>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

3 - 6

Valid until: Dec 29th, 2014 2:00PM