Avalanche Forecast

Issued: Jan 26th, 2018 4:00PM

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

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

We have reached the tipping point for avalanches. Natural activity has slowed down, but the snowpack is perfectly primed for human triggering. Step way back in terms of your terrain use and exposure.

Summary

Weather Forecast

Temps. will be in the -5 to-10C range for Saturday, and slightly cooler in the alpine. At treeline we could see 10-15cm in Kootenay, 5-10 in Lake Louise, and 3-5cm in the Banff by the end of the day, with light to mod. S - SW upper level winds (3000m). An "atmospheric river" may enter our region Sunday night which could cause an avalanche cycle.

Snowpack Summary

55-75cm of snow has fallen over the past 10 days creating a lot of loose snow on the surface. Alpine winds have distributed this into leeward areas with wind slabs up to 1m thick. Three persistent weak layers lurk in the upper half of the snowpack: Jan 16 down 20-40cm; Jan 6 down 30-50cm; Dec15 down 40-80cm giving easy-mod test results.

Avalanche Summary

There was a fairly widespread avalanche cycle yesterday to size 3 with wind slabs and persistent slabs failing. Less activity Friday but still some sporadic size 2-3 persistent slabs failing in the region.

Confidence

Problems

Persistent Slabs

There are 3 weak layers in the upper snowpack: Jan 16, Jan 6, and Dec. 15. All are a mix of sun crust, surface hoar and facets depending on your aspect and elevation. Avalanches are occurring on these layers

Use conservative route selection, choose supported terrain with low consequence.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Wind Slabs

With up to 75cm of snow over the past 9-days there is plenty of wind slab development available to be blown into touchy windslabs which should be anticipated in alpine and treeline areas.

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

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Jan 27th, 2018 4:00PM