Avalanche Forecast

Issued: Feb 15th, 2016 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.

Ian Jackson, Parks Canada

Banff Yoho Kootenay.

We have a classic Rockies snowpack with persistent weak layers right now and numerous close calls over the last week prove this. Have patience and stick to conservative terrain for a while until the snowpack settles out!

Summary

Weather Forecast

The jet stream is over us so expect to get regular snow throughout the week. We should get 5-10 cms Monday night with a clearing trend Tuesday. The next storm will come in on Wed around noon and we should see 5-10 cms into Thursday. Freezing levels will remain around 1200m with a slight warming trend on Wed. Alpine winds will be moderate W/SW.

Snowpack Summary

Fresh windslabs and cornice growth in the alpine with 15 to 30 cm of recent snow and west winds. A 50-100 cm slab overlies the January 6th weak layer of surface hoar, facets and sun crust and snowpack tests indicate an unstable bond between the two. The lower snowpack is facetted and quite weak in thinner areas (<1.5m) and settled in thicker areas.

Avalanche Summary

Close calls continue - on Monday the 15th, two climbers triggered a size 2 slab on the approach to "Nightmare on Wolf Street" on the Stanley Headwall. This failed on the ground and would have been an ugly ride. Last Friday, a group of 8 triggered a size 2 just left of the regular final approach slope to Bow Hut

Confidence

Due to the number of field observations

Problems

Persistent Slabs

50-100 cms of snow overlies the Jan 6th layer of surface hoar, facets and sun crust. Numerous reports of avalanches triggered on this layer over the last 5 days. In thinner areas, isolated avalanches have scrubbed to ground.

Avoid areas with overhead hazard.Avoid paths that have not avalanched recently.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Wind Slabs

Be mindful of cross loaded features and the lees of ridges where fresh windslabs 10-40 cm thick have recently formed. If triggered, there is potential to step down to the persistent weak layer and to ground in thin areas.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 16th, 2016 4:00PM