Avalanche Forecast

Issued: Jan 3rd, 2013 4:09PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

The inversion is gone, but winds have picked up and are forecast to blow from the NW. This may raise the hazard in localized areas where there is still snow available for transport. Ice climbers pay attention to loading in the bowls above you!

Summary

Weather Forecast

The ridge is breaking down, bringing an end to the nice weather we've been experiencing, but giving hope of some new snow by Sunday!Fri: Alpine temps ~ -8. Alpine winds mod to strong NW. Overcast with trace accumulations.Sat.: Alpine temps ~-5. Alpine winds light to moderate W. Cloudy.Sun: Alpine temps ~ -10. Winds light SW. Up to 5 cm snow!

Snowpack Summary

Hard wind slabs exist in exposed alpine features but haven't been reactive to skier traffic. Suface hoar is growing in sheltered treeline locations. W of the divide, a well settled snowpack exists with the basal Nov 6 crust well bonded. In the front ranges E of the divide, a facetted snowpack exists with the Nov 6 basal crust being mainly facetted.

Avalanche Summary

A sunshine snow safety team member triggered a cornice while approaching the ridge to do cornice control. The cornice dropped onto steep terrain, triggering a size 2 that failed on a recent wind slab layer. Otherwise, no new avalanches.

Confidence

Problems

Cornices

The cold temperatures are facetting out cornices and large cornice failures have been observed. Currently there is an objective hazard from natural cornice failures as well as a hazard from human triggering while walking on ridges.

Give cornices a wide berth when travelling on or below ridges.Pay attention to overhead hazards like cornices.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Wind Slabs

Moderate winds have created hard windslabs in exposed alpine terrain. Although these have not been reactive to human traffic, they may become more reactive as the alpine temps increase.

Be cautious as you transition into wind affected terrain.Caution in lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Loose Dry

This problem exists mainly in thin snowpack areas E of the divide where the snowpack has completely facetted and lost all cohesion. Watch for sloughing in steep terrain where the snow is unsupportive, particularly as temps increase.

Be cautious of sluffing in steep terrain.Avoid travelling on ledges and cliffs where sluffing may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 4th, 2013 4:00PM