Avalanche Forecast

Issued: Jan 11th, 2019 4:00PM

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

tim haggarty, Parks Canada

Banff Yoho Kootenay.

The recent storm snow is settling rapidly with warm temps and contributing to the significant slab sitting over weak basal facets and depth hoar. Warm temps will keep these slabs sensitive to human triggering in the thinner snowpack areas.

Summary

Weather Forecast

Freezing levels are forecast to approach 2200m daily through Monday which may keep slabs sensitive to human triggering. Watch for potential temperature inversions. Moderate to Strong SW winds should start to diminish Saturday and it looks to be cloudy near the divide until Monday when the potential for solar inputs looks likely.

Snowpack Summary

Snowfall since Jan2 has been redistributed by southwest winds yielding extensive wind effect in the alpine. In thick snowpack areas, the Dec 10th weak layer of facets is now down 100-150cm with a stronger snowpack below. In thin snowpack areas, there is little separation between Dec 10 and the weak depth hoar/ facets sitting 40 cm above the ground.

Avalanche Summary

A group just outside of the Lake Louise ski area above the Pika Flats at treeline triggered a sz 2 slab 80cm deep failing 40m wide and running 200m on a SW aspect today. The snow safety team at Sunshine Village saw several windslabs fail in the last 24 hrs one of which scrubbed to the ground and produced a large avalanche off of the Monarch.

Confidence

Freezing levels are uncertain on Saturday

Problems

Deep Persistent Slabs

The facets and depth hoar 40 cm above the ground inspire little confidence. Some large natural avalanches are still occurring and human triggering is likely. This layer needs time to adjust to the load and this problem will be around for some time.

Be aware of the potential for wide propagations which could result in large avalanches.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3.5

Wind Slabs

Moderate to strong SW winds have moved a significant amount of snow over the last three days. Expect widespread wind effect in the alpine and get your guard up as you enter open areas at treeline.

Use caution in lee and cross-loaded terrain near ridge crests.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Valid until: Jan 12th, 2019 4:00PM