Avalanche Forecast

Issued: Apr 14th, 2015 4:00PM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Wind Slabs and Cornices.

ian jackson, Parks Canada

Banff Yoho Kootenay.

Although we have switched to 'Spring Conditions", the recent series of storms have brought back more winter-like avalanche problems. Give the "big lines" a rest and assess the local stability from smaller terrain before committing to bigger terrain!

Summary

Weather Forecast

A fast moving system will drop 5-10 cm Tuesday night. Wednesday through Friday we should see a mix of sun and cloud with minimal precipitation and cool temperatures. The big story this week will be the wind, with moderate to strong W/ NW winds starting Wednesday PM which will cause further windslab development.

Snowpack Summary

30-50 cm of recent storm snow has been blown into windslabs in many areas at treeline and above. Although the cloud cover has kept the sun effect to a minimum, these windslabs are expected to be a problem in leeward areas for a few days. This overlies crusts in most areas, which appear to be providing some strength over the deep facet layers.

Avalanche Summary

A very close call yesterday with a solo skier triggering a size 2 windslab avalanche on a N aspect in the alpine on Cathedral mountain. The skier went for a ~300m ride and was partially buried with some gear broken. He was lucky to walk away with minor injuries. This is indicative of the windslab problem that has formed over the last few days

Confidence

Problems

Wind Slabs

Strong winds have redistributed the recent 30-40 cm of snow that has fallen. Heads up for fresh windslabs in high alpine areas and near ridgecrests. Assess the bond of the new snow on low consequence slopes before committing to bigger terrain.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

There have been many reports of cornice chunks falling off of ridge crests which may be big enough a load to trigger an avalanche on the basal facets, or be enough mass to be a hazard themselves.

Stay well back from cornices.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 15th, 2015 4:00PM