Avalanche Forecast

Issued: Nov 29th, 2014 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Natural activity has slowed down after the big storm, but conditions are prime for human triggering due to the deeper weak layers. Choose very conservative terrain. SH

Summary

Weather Forecast

Cold and clear on Sunday with temperatures in the mid minus 20's. We will see a slight warming trend through the forecast period and alpine winds shifting to a W/NW flow.

Snowpack Summary

Storm snow amounts over the last few days: 40cm in the Kootenay region, 50cm in the Lake Louise area, and 60 cm at Sunshine. 2 layers of concern, the Nov. 6th rain crust/facets 20-30cm above the ground, and the Nov 24th facet layer 25-50 cm above the ground. The new load of storm snow is overloading these layers.

Avalanche Summary

A natural cycle to sz. 3 on all aspects at treeline and above occurred during the storm. Explosive control at Sunshine and Lake Louise ski areas have been producing avalanches up to size 2.5. There is also extensive whumpfing at all elevations and aspects. A notable size 2.5 and size 2 were likely remote triggered in West Bowl in Lake Louise today.

Confidence

Due to the number of field observations on Saturday

Problems

Persistent Slabs

The new snow load has overloaded the weaker rain crust/facet layers below. Cold temperatures have helped tighten the snowpack, but we will see this condition persist. Below treeline features are less reactive but avoid steep, open features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Wind Slabs

Upper elevation winds during the storm have formed wind slabs which can step down to deeper layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 2

Valid until: Nov 30th, 2014 4:00PM