Avalanche Forecast

Issued: Feb 15th, 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.

Tricky conditions - skier triggered size 2.5 today and many large avalanches over the past 4 days. Give avalanche terrain that has not had a large avalanche a wide berth.

Summary

Weather Forecast

The temperatures will drop through the day on Thursday and will be accompanied by some more new snow (5 cm probably).

Snowpack Summary

45 cm of settled snow has formed a cohesive slab overlying a series of weak layers. Test results indicate "sudden" shear failures on these layers, which indicates that they are primed for triggering. Recent strong winds and warm temperatures have tipped the balance, and most slopes that have not avalanche should be considered highly suspect.

Avalanche Summary

Skier triggered a size 2.5 avalanche

on West aspect, in Lipalian 2 outside Lake Louise ski area. Numerous large deep avalanches over the past 4 days. Avalanche control on Tuesday produced an impressive size 3 avalanche on Vermillion Peak.Â

Confidence

Problems

Wind Slabs

Strong to extreme wind on Sunday created wind-slabs and cornices that are ripe for triggering. Slabs are becoming firmer in high start zones. Give avalanche terrain a wide berth as fracture lines may extend further that you expect.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

The new snow has created a touchy slab over the weak facets at all elevations. Avalanches could run full path. We are seeing avalanche activity for the first time this season in many different areas.

Minimize overhead exposure; avalanches may reach the end of run out zones.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Feb 16th, 2017 4:00PM