Avalanche Forecast

Issued: Feb 8th, 2018 4:00PM

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

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

http://www.pc.gc.ca/apps/links/goto_e.asp?destination=Avoid all avalanche terrain including crossing runout zones at valley bottom. Natural activity will likely taper over the next couple of days, but human triggering will be as touchy as it gets.

Summary

Weather Forecast

The epic storm has ended and we will see a few "normal" days of weather. -15 to -18C in the alpine Friday with light winds and mainly clear skies and no additional snow.

Snowpack Summary

Thursdays storm dropped 30 - 50cm with variable winds. This combined with other recent snow has overloaded the 3 main mid pack concerns which are the Jan 16th, Jan 6th, and Dec.15 weak layers. These are a mix of facets, crusts and surface hoar and can be found 70cm to over 150cm deep in the snowpack and are currently producing very easy results.

Avalanche Summary

Another widespread cycle Thursday to size 3.5 (what we could see) . These were failing on the above mentioned weak layers. Explosive control was producing size 3 avalanches up to 150cm deep with just the explosive hitting the slope. Most of these avalanches are traveling far into the valley bottom which should be a concern for all users.

Confidence

Problems

Persistent Slabs

Three weak layers exist in the mid 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. These layers are very sensitive to triggering both naturally and by human triggering.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 4

Storm Slabs

There are storm slabs up to 1m thick on many aspects and elevations from the big storm on Thursday. These will be highly sensitive to triggering and once initiated, can step down to the deeper persistent layers causing very large avalanches.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Valid until: Feb 9th, 2018 4:00PM