Avalanche Forecast

Issued: Nov 16th, 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.

chris gooliaff, Parks Canada

Banff Yoho Kootenay.

High winds, mild temp's, and anywhere from 5-20cm will increase the avalanche danger by Sunday. Pay particular attention to areas of heavier snowfall.

Summary

Weather Forecast

On Saturday, winds and temp's are expected to rise, with strong/extreme SW winds and freezing levels up to 1900m midday. 15cm possible by Saturday night in northern areas of region (Bow Summit). Sunday, cooling with continued strong winds and 5-10cm.

Snowpack Summary

Continued settling of the surface snow over the Nov crusts, which are buried 20-50cm below the surface.Â The surface snow varies from soft to hard slab in lee features, while some unconsolidated snow still exists in sheltered locations.Â Below the crusts, a settled base exists.

Avalanche Summary

No new observations in Yoho today. Ski hill avalanche control on Sunshine and Lake Louise produced no notable results.

Confidence

Forecast snowfall amounts are uncertain

Problems

Wind Slabs

Wind slabs sitting on the Nov 6 crust have become more stubborn to trigger in the last few days. This could change with the warm temperatures forecasted, accompanied by up to 10-20 cm's of snow.

Avoid freshly wind loaded features.Be careful with wind loaded pockets while approaching and climbing ice routes.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

Deep slabs size 2-3 have been noted on isolated steep alpine slopes over the past week. Failure plane was at the bottom of the snow pack on firn or glacier ice. No new have been reported these last few days but are still possible in the high alpine.

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 17th, 2012 4:00PM