Avalanche Forecast

Issued: Dec 20th, 2012 4:00PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

Mod. to strong winds from the S/SW are creating a fresh instability to watch out for. Periods of strong winds will also increase sluffing out of steep terrain (ice climbers beware). Winds should ease on Friday allowing the danger to decrease.

Summary

Weather Forecast

Thurs overnight: Alpine temps -10/-15. 2-5 cm snow. Alpine winds moderate from the SW.Fri: Alpine temps -10/-15. Clearing skies, trace precip. Alpine winds light from the SW.Sat: Alpine temps -10/-15. Overcast, trace precip. Alpine winds light from the S.Sun: Alpine temps -10/-15. Overcast, trace precip. Alpine winds light from the SW.

Snowpack Summary

10-20 cms of new snow overlies a well settled midpack. At ridgetop elevations, moderate to strong S/SW winds are forming 15-30 cm soft slabs in the immediate lee on N through E aspects. The Nov. 6th crust is facetting out, and is now more of a facet layer than a crust in many places. This layer is giving hard to no results in compression tests.

Avalanche Summary

Limited observations by Parks staff today.Â Reports of ski cutting soft slabs in wind loaded areas by ski patrol at Sunshine and loose snow sluffing out of steep terrain with increased winds.

Confidence

Due to the number of field observations on Thursday

Problems

Wind Slabs

10-20 cms of new snow along with mod. S/SW winds is creating slabs up to 40 cms thick in immediate lees at ridgetop elevations. This new instability has been reactive to skier traffic with ski cutting to size 1.5.

Be cautious as you transition into wind affected terrain.Stay off recent wind loaded areas until the slope has had a chance to stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 21st, 2012 4:00PM