Avalanche Forecast

Issued: Jan 28th, 2017 4:00PM

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

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

With elevated winds, we are seeing isolated natural avalanches that are hard to predict. Be suspect of slopes where a slab sits over the weaker layers below, and watch how any winds are loading alpine features. SH

Summary

Weather Forecast

West winds could reach 100kph at 3000m and temperatures will be in the -5C to -9C range for Sunday. 5-8cm is currently in the forecast for Monday.

Snowpack Summary

10 to 20cm of wind blown snow from last week overlies a generally weak and facetted mid-pack and base - particularly in the Lake Louise area and on the E side of Hwy 93N. Near the divide,deeper snowpacks are stronger and more supportive. Surface hoar up to 10mm was buried by a trace in some areas and blown away in others by strong W winds Saturday.

Avalanche Summary

Yesterday a new 300m wide fracture line was spotted at treeline/low alpine near Cathedral Peak. This was a N-NE aspect and was 50cm deep. A few other healthy sized 2 slides were noted in the Lake Lousie backcountry today. 2 were new wind slabs, and 1 was a deep persistent slab on Fossil Peak. We suspect the increase in winds triggered the slides.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Sunday

Problems

Deep Persistent Slabs

The snowpack is so weak, we don't trust slopes where a slab sits over the deeper weak layers. Avoid steep slopes with this structure. Continued conservative choices will remain important for some time.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

New wind slabs have been reactive in the Lake Louise region near ridge top in the last 24 hours. These will likely remain reactive in the short term while winds speeds stay elevated.

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 29th, 2017 4:00PM