Avalanche Forecast

Issued: Jan 11th, 2018 4:00PM

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

grant statham, Parks Canada

Banff Yoho Kootenay.

The snowpack has almost reached tipping point - but not quite - with 40cm of soft snow overlying the Dec 15 weak layer (surface hoar & facets) we just need a slight change to the overlying slab density to have an avalanche cycle. Be careful!

Summary

Weather Forecast

Friday will continue to be cold and clear with overnight lows of -20 and daytime highs reaching -13. No precipitation in the forecast for Friday and winds will be light from the northwest.

Snowpack Summary

30 cm of low density snow has fallen over the past 5 days with limited wind effect except near alpine ridge crests. There is now a total of 30-50 cm overlying the Dec 15 persistent weak layer which is becoming reactive at treeline and above. We are closely monitoring the overlying slab properties and watching for the snow to become more dense.

Avalanche Summary

A solo backcountry skier triggered a size 2 avalanche on Richardson's Ridge today outside the Lake Louise Ski Resort boundary - this was a treeline area with a shallow snowpack. As well, numerous small windslabs were observed to have run over the past 48 hours during the recent storm.

Confidence

Problems

Persistent Slabs

There is a dangerous weak layer down 30-40 cm but it needs a stiffer slab overlying it for the avalanche to occur. We are "almost" at that tipping point so be very careful with this layer and travel conservatively even if you observe no avalanches.

Choose conservative lines and watch for clues of instability.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Wind Slabs

Soft windslabs formed during the last storm exist near ridge crests and under cliff bands. Watch for the changing feel of the snow under your feet and be wary of areas with denser surface snow.

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