Avalanche Forecast

Issued: Dec 27th, 2014 4:00PM

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.

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

Better skiing can be found due to the recent, however there is a poor bond at the storm snow interface and the overall snowpack is quite weak. Avoid larger features in steeper terrain. SH

Summary

Weather Forecast

A gradual cooling trend over the next few days with temperatures reaching the-20's by Monday. Expect only trace amounts of snow. Light alpine winds from the East/NE through the forecast period.

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

Following the storm last week avalanches up to size 2.5 were observed with propagations up to 200 m, occasionally stepping down to the basal facets/crusts.There was significantly less avalanche activity around the Banff area. The Lake Louise region and West received the bulk of the snow with a subsequent increase in activity.

Confidence

Due to the number and quality of field observations on Saturday

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

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

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.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 28th, 2014 4:00PM