Avalanche Forecast

Issued: Mar 21st, 2013 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Watch for thin areas especially East of the divide where triggering deeper slabs over facets can cause large avalanches. SH

Summary

Weather Forecast

Light N winds, freezing levels hovering around valley bottom, and only light snow tomorrow.Â We may see more sun through the weekend which may trigger an avalanche cycle on solar aspects within the new snow.

Snowpack Summary

W of Divide: Tak study plot (Yoho) today @1800m.Well settled 230cm snowpack. 30cm moist layer (rain event last week) buried under 30cm low density snow. Up to 40cm snow in last 48 hrsÂ at TL. (E-Mod shears). E of Divide:harder wind slabs over a variety of surfaces from sun crust, facets, and depth hoar. Sensitive to human triggering in thin areas.

Avalanche Summary

A report of a remote triggered sz.3 in the observation peak area (East of hwy. 93 N) on a SW aspect in the alpine March 20.Â It was up to 175cm deep on a basal weakness and was 200m wide.Â Â A similar sized slide in the Redoubt area in the Lake Louise backcountry (E of Divide) occurred on the 19th.

Confidence

on Friday

Problems

Storm Slabs

Slabs up to 60cm thick are slowly bonding to the old surfaces. These will be more sensitive to triggering from thinner areas East of the divide, but are present everywhere. Solar aspects over all regions will have these slabs sitting over sun crust.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

We have been seeing activity on the basal facets East of the divide over the recent week. One report of a sz. 3 remote triggered in the observation peak area.

Remote triggering is a concern, watch out for adjacent slopes.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Some large diving boards have been seen to fail in the last few days which will be augmented this weekend with solar input.

Pay attention to overhead hazards like cornices.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 22nd, 2013 4:00PM