Avalanche Forecast

Issued: Nov 11th, 2012 4:00PM

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.

snow safety, Parks Canada

Banff Yoho Kootenay.

Early season conditions exist. Go easy. The larger avalanches observed on steep northerly slopes indicate things may be more touchy in the high alpine.. JBW

Summary

Weather Forecast

Westerly flow will develop with warming temperatures and light snowfall. Wind transport in open areas likely. Temps -4 to -10 Winds SW 20-40km/hr

Snowpack Summary

Lots of wind effect and wind slabs n open areas. Some slabs pulling out on Nov 6th Crust which is down approx 30cm. Crust is absent above 2700m. Snowpack is 1F and supports skiers at and above treeline. (Depth 60-120cm)

Avalanche Summary

Some controlled (Sc/Xe) slabs in uncontrolled areas at ski hills up to size 2: 30-60cm thick failing on Nov 6 crust. Several larger size 2-3 slabs observed today failing on firn snow about 1meter down in alpine locations along Wapta traverse

Confidence

Intensity of incoming weather systems is uncertain on Tuesday

Problems

Wind Slabs

Wind slabs 20-50cm thick near lees of ridgecrests are sitting on the Nov.6 crust and failing in steeper locations with ski cuts and explosives, More prevalent on north and east, but can be found on all aspects due to the easterly loading.

Avoid lee and cross-loaded terrain near ridge crests.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

Several deep slabs size 2-3 have been noted on steep alpine slopes around Lake louise and on the Wapta. These have failed at the bottom of the snow pack on firn or glacier ice.

Use caution on N and E aspects.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 12th, 2012 4:00PM