Avalanche Forecast

Issued: Mar 25th, 2015 4:44PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Winds picked up through the day on the Wapta and in the Lake Louise area. Watch for continued windslab development and rising freezing levels over the next few days.

Summary

Weather Forecast

Expect a good freeze tonight followed by light flurries for Thursday-Sunday with moderate to strong SW wind. Accumulations will range from 5-20 cm with the greatest amounts occurring West of the Divide and in the Northern part of the region. Freezing levels rise to 2300-2600 m for Thursday and Friday nights.

Snowpack Summary

Convective cells have dropped 10-20 cm's earlier in the week. Windslabs exist in isolated immediate lee features and open areas in the alpine and sit on a variety of hard surfaces. The base of the snowpack is made up of facets and depth hoar and remains weak.

Avalanche Summary

A few small windslab avalanches triggered by explosives or skiers occurred earlier in the week. No new avalanches reported or observed today. Temperatures remained cool again today - no pinwheeling observed and crusts remained intact.

Confidence

Problems

Wind Slabs

There is generally 10-20 cm available for transport and moderate to strong SW wind continues to build windslabs. They are sensitive to human triggering on features such as ridge crests, cross loaded gullies, and steep terrain features.

Be cautious as you transition into wind affected terrain.Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The lower half of the snowpack is weak due to the presence of basal facets and depth hoar. This layer has been dormant lately but may become more sensitive with the added snow load from wind and new snow, especially in thin areas.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 3

Valid until: Mar 26th, 2015 4:00PM