Avalanche Forecast

Issued: Dec 15th, 2018 4:41PM

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

Tim Haggarty, Parks Canada

Banff Yoho Kootenay.

Continued natural activity today with touchy slabs at all elevations reacting easily to skier and explosive triggers. Avoid avalanche terrain. Avalanche control is planned on Mt Dennis and Mt Whymper Sunday. No skiing or climbing in these areas.

Summary

Weather Forecast

Winds and snow are forecast to back off overnight Saturday as a ridge brings cooler temps near -16C at 2000m. Temps will climb to -10C as winds pick back up to moderateÂ SW later on Sunday. On Monday, expect temperatures to climb a bit and winds to stay elevated in the moderate range as the next wave of precip arrives from the Coast.

Snowpack Summary

40 - 60 cm of snow since Dec 10 forming a storm slab over facets and surface hoar. New windslabs are common on lee (mostly east) aspects. The lower snowpack is weak and facetted with some avalanches running to ground.

Avalanche Summary

Skier triggered avalanches at Emerald Lake and Wawa Bowl near Sunshine today with another close call in West Bowl at Lake Louise yesterday. Numerous natural and skier or explosive triggered avalanches over the past few days up to size 2.5 have been reported. Avalanches may run further downslope than expected, so be cautious of overhead hazard.

Confidence

Intensity of incoming weather systems is uncertain on Monday

Problems

Storm Slabs

Up to 40 cm of recent snow along with strong winds will have created storm slabs and wind slabs at all elevation. These slabs are reactive to skier triggering and are running long distances. Ice climbers pay attention to overhead hazard.

Avoid all avalanche terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

The mid and lower portions of the snowpack are weak and are now overloaded with critical levels of snow. We expect avalanches to step down to this deeper layer.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 3

Valid until: Dec 16th, 2018 4:00PM