Avalanche Forecast

Issued: Feb 5th, 2018 4:00PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Persistent Slabs and Storm Slabs.

Ian Jackson, Parks Canada

Banff Yoho Kootenay.

Conditions are touchy right now. Somewhere between High and Considerable and forecasters are debating which category they fall into. Regardless, it is a good time to stay out of avalanche terrain!

Summary

Weather Forecast

Tuesday should be mostly clear with light winds. The next storm is moving in Wednesday/ Thursday with 20-30 cm 's of snow, rising temps and strong west winds. We expect the danger to rise significantly at that time.

Snowpack Summary

20 - 30 cm of low density snow with little wind sits on the surface. The main concern in the snowpack lurks below and continues to be the 3 persistent weak layers of surface hoar and/or facets that are found between 50 and 100cm down. We continue to observe sudden test results, whumphing and large propagations on these layers.

Avalanche Summary

Forecasters remote triggered a size 2.5 today on the Icefields Parkway. They triggered it from ~ 50m away on a low angle ridge. The slide was ~ 300m wide, 80 cm deep and slid on a well preserved surface hoar layer (Jan. 6th). A solo skiier in the Lake Louise backcountry had a very close call today when he triggered a size 2 and was partially buried

Confidence

Intensity of incoming weather systems is uncertain on Wednesday

Problems

Persistent Slabs

Three weak layers exist in the upper snowpack: Jan 16, Jan 6, and Dec 15. All are a mix of sun crust, surface hoar and facets depending on the aspect and elevation. 50-100 cm of snow over the last week has overloaded these layers.

Avoid all avalanche terrain.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 3.5

Storm Slabs

20-40cm of storm snow (and wind) has developed a slab at higher elevations. If triggered this layer has the potential to step down to deeper instabilities. Continue to make conservative route choices.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.The new snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 6th, 2018 4:00PM