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Avalanche Forecast

Dec 20th, 2012–Dec 21st, 2012
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Purcells.

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. 

Avalanche Problems

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