Avalanche Forecast

Issued: Jan 13th, 2014 5:04PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

The natural avalanche cycle is expected to taper off but the new slab formed by storm snow over the basal facets will likely continue to create large avalanches for some time. Avoid all avalanche terrain for the next while until things settle down!

Summary

Weather Forecast

Moderate to strong W winds with strong gusts are expected to continue for the next 2 days with cloudy skies. The precipitation has ended. Alpine temperatures will be around -7C with overnight lows of -10. Winds will abate by Thursday and skies will become a mix of sun and cloud.

Snowpack Summary

Up to 80 cm of storm snow has fallen over the last few days, combined with very strong winds. Deep storm slabs have formed from new snow and wind loading; in excess of 120 cm in leeward areas. These slabs are overloading a weak, facetted snowpack. The precipitation has ended, but strong gusty West winds are expected to continue for the next 2 days.

Avalanche Summary

Large avalanches to size 3 continue to occur with some running full path. A size 2 in White Rabbit (near Louise ski area) released to ground, causing several sympathetic size 1's. Numerous human triggered avalanches were reported adjacent to ski areas including Ptarmigan Chutes today and Maintenance Cliffs and a close call on Wawa Ridge yesterday.

Confidence

Problems

Deep Persistent Slabs

The possibility of natural and skier triggered avalanches remains high. Stay out of avalanche terrain until things settle down. Look for protected skiing in the trees on moderate angled slopes with no exposure to alpine and tree line start zones.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

Storm Slabs

The storm slab is 40-50cm thick in many places and if triggered, it is likely to step down into the basal facets resulting in very large avalanches. Avoid all avalanche terrain until this cycle subsides.

Avoid freshly wind loaded features.Use caution in lee areas in the alpine and treeline. Recent storm snow has formed touchy slabs.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Jan 14th, 2014 4:00PM