Avalanche Forecast

Issued: Dec 20th, 2012 9:15AM

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

Avalanche Canada ghelgeson, Avalanche Canada

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Purcells.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Friday: Light to moderate S/SW winds.  Treeline temp -10. Occasional flurries. Freezing Level: Valley bottom.Saturday: Light to moderate S/SE winds. Treeline temp -12.  Occasional flurries increasing to light snow around sunset. Freezing Level: Valley bottom.Sunday:  Light west winds.  Treeline temp -8.  No snow.  Freezing Level: Valley bottom.

Avalanche Summary

Avalanche observations from Wednesday were limited to isolated sluffing from north facing alpine terrain in the Southern Purcells.

Snowpack Summary

The recent storm deposited 15-20 cms in the North of the region near Golden, and 20-50 cms further South near the Purcell Wilderness Conservancy.  Moderate to strong winds Wednesday/Thursday created windslabs 20 - 60 cm in depth at and above treeline.  Windslab distribution and size is wildly inconsistent across the region, but it feels like they grow in size as you travel further south.  There is some talk about a December 16th surface hoar layer, but it's distribution is *very* spotty. 

Problems

Wind Slabs

An icon showing Wind Slabs
Continued light snowfall with moderate SW winds will add to the wind slab problem.  These slabs range from 20 cm in the North to 60 cm in the South of the region.  They may be sensitive to the weight of a sled or skier.
Use ridges or ribs to avoid pockets of wind loaded snow.>Stay off recent wind loaded features for a few days, these slopes need time to stabilize.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Dec 21st, 2012 2:00PM

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