Avalanche Forecast

Issued: Nov 12th, 2012 4:31PM

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

Brian Webster, Parks Canada

Banff Yoho Kootenay.

Summary

Weather Forecast

Mixed sun and cloud for next few days. Freezing Levels rising to ~1200m on Tuesday. Light to moderate westerly winds.

Snowpack Summary

Up to 35 cm of recent storm snow has formed widespread wind slabs in the alpine and is sitting overtop of the Nov 6 rain crust. November 6 crust is well developed at treeline elevations but was not found above 2700 m. At treeline average snowpack depth is 70 cm deep.

Avalanche Summary

No new naturals today. Ski hills reporting slabs up to Class 2 with explosives running within storm snow or on Nov. 6 crust.Â Class 2 slab on St NichÂ (reported yesterday) ran on firn snow and was human triggered. See Facebook link below for picture.

Confidence

Problems

Wind Slabs

Widespread wind slabs (20-50cm thick) in the alpine are sitting on the Nov.6 crust and are reactive to skier triggering in steeper locations. More prevalent on north and east, but can be found on all aspects due to the easterly loading.

Be careful with wind loaded pockets while approaching and climbing ice routes.Avoid lee and cross-loaded terrain near ridge crests.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

In helicopter flight over the Wapta on Sunday several deep slabs size 2-3 were been noted on steep alpine slopes . These have failed at the bottom of the snow pack on firn or glacier ice. See avalanche report.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Nov 13th, 2012 4:00PM