Avalanche Forecast

Issued: Dec 26th, 2014 4:04PM

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

Conrad Janzen, Parks Canada

Banff Yoho Kootenay.

The skiing has improved due to recent snow, however there is a poor bond at the storm snow interface which will persist for some time and the snowpack overall is very weak. Avoid larger features, and steeper terrain. Enjoy the lower angled terrain.

Summary

Weather Forecast

A few flurries overnight then a clearing and cooling trend starts on Saturday. Clear skies, light NE winds and cold temperatures are forecast for Sunday and Monday.

Snowpack Summary

Recent winds have created small wind slabs in the alpine which sit over the Dec 18 layer of crust, facets and/or surface hoar depending on the location. A poor bond exists at this interface. At the base of the snowpack weak crusts and facets exist which are still a concern.

Avalanche Summary

"Speed Run" at Lake Louise ran naturally as a size 2 on December 26th following some moderate wind transport overnight. A couple other natural avalanches up to size 2 were also observed. Following the storm last week avalanches up to size 2.5 were observed with propagations up to 200 m, and occasionally stepping down to the basal facets/crusts.

Confidence

Problems

Persistent Slabs

15 to 30cm's of snow from last week is bonding poorly to previous surfaces and remains reactive to skier triggering, especially in areas where there is some wind loading and slab development. This is more of a problem in the western areas of the park

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.The new snow will require several days to settle and stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

A weak and facetted basal layer exists at the bottom of the snowpack. Smaller storm snow avalanches may step down to this weak layer.

Use careful route-finding and stick to moderate slope angles with low consequencesBe aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 27th, 2014 4:00PM