Avalanche Forecast

Issued: Mar 22nd, 2013 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.

snow safety, Parks Canada

Banff Yoho Kootenay.

Nice weather this weekend will tempt people to step out into bigger terrain. Avoid steep, thin snowpack areas, especially East of the divide where triggering of large avalanches is possible. SH

Summary

Weather Forecast

Light Northerly flow with weak convective afternoon buildup Saturday.Â No new snow in the forecast and minimal solar effect with freezing levels up to 1600m.

Snowpack Summary

W of Divide: Generally well settled snowpack in deeper areas. Previous storm slabs buried by 20-40cm at TL and above. Â Some whumpfing today at ridgetop in thinner areas on facets above Vermillion crossing. 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

Deep persistent slab avalanches have been occurring on basal facets this week. One such avalanche was remote triggered in the Observation Peak area and was up to 175cm deep. Click here for another avalanche on Redoubt Mountain (E of divide) from March 19th.Â Obs. from Yoho today saw natural slabs up to 2.5 within the recent storm snow in the Alp.

Confidence

Due to the number of field observations on Friday

Problems

Persistent Slabs

Watch out for thin areas especially East of the divide where it is possible to trigger or remote trigger deep slabs on basal facets or crusts. Be conservative with terrain choices in bigger terrain.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

New windslabs have formed on lee aspects, much thicker West of the divide where more new snow has fallen. Up to 40cm was reported over the last few days in Yoho, followed by a wind event on the 21st. Crown depths of 60cm reported there,

Avoid freshly wind loaded features.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Mar 23rd, 2013 4:00PM