Avalanche Forecast

Issued: Feb 17th, 2017 4:00PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

http://www.pc.gc.ca/apps/scond/Cond_E.asp?oID=26206&oPark=100092 Tricky and dangerous avalanche conditions exist. The potential to trigger large avalanches persists. Conservative route choices are recommended.

Summary

Weather Forecast

Saturday will be mainly cloudy with some isolated flurries. Freezing levels will drop to surface tonight and rise to 1500 m for Saturday through to Sunday. Flurries predicted to continue through the weekend with light South wind. Freezing levels may hold around 1500 m with light showers expected below this elevation.

Snowpack Summary

40-60 cm of snow in the past week combined with moderate SW winds has created new reactive windslabs on lee and crossloaded features. This rests on hard windslabs which overlie a structurally weak snow pack. Test results show sudden planner failures in the storm snow and basal depth hoar Below 1800 m the snowpack is moist from rain event on Thur.

Avalanche Summary

In the last 24 hrs, two large avalanches outside the Lake Louise and Sunshine ski area boundaries and stepped down to the ground. Skihills reported several smaller windslab avalanches near ridgetops. A Skier triggered a size 2.5 avalanche on Lipalian 2 (west aspect) outside Lake Louise ski area occurred on Wednesday.

Confidence

Freezing levels are uncertain

Problems

Wind Slabs

Fresh snow and moderate SW winds have created touchy windslabs in alpine and open terrain near treeline.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

The recent storm snow has created a touchy slab over the weak faceted midpack at all elevations. Avalanches on this layer could run full path. Extra caution is warranted until the snowpack has adjusted to this extra load.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Feb 18th, 2017 4:00PM