Avalanche Forecast

Issued: Dec 21st, 2016 8:19AM

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

danyelle magnan, Parks Canada

Glacier.

Don't let lowering danger ratings fool you. Natural avalanche activity will decrease but human triggering is still likely. Conservative terrain selection and safe travel practices (ie ski one at a time and choose safe regroups) are strongly advised.

Summary

Weather Forecast

The brunt of the storms have passed. Today should be cloudy with possible sunny breaks. Moderate to strong SW winds will continue to transport snow, adding to windslabs and cornices. Thurs a weak storm will bring ~5cm of snow with strong SW winds. On Fri, flurries will taper off and we may see some sun as another cold, high pressure system develops

Snowpack Summary

~80cm of storm snow is settling into a slab and in exposed areas strong S'ly winds have formed windslabs. These new slabs sit on the Dec 18th interface: facets and in some areas surface hoar. All of this sits on a weak, facetted snowpack. Field teams reported shooting cracks and tests on the Dec 18th layer indicate that it is touchy.

Avalanche Summary

Yesterday a skier was partially buried by a skier accidental size 1 avalanche in the Asulkan. It was 30-50cm deep and failed on the Dec 18th (see their MIN). They also remotely triggered a size 1.5 on a SW aspect. Numerous natural avalanches, mostly size 2.5 but a few size 3, were observed from steep, lee start zones, running to valley bottom.

Confidence

Problems

Storm Slabs

~80cm of storm snow is settling into a slab. It sits on a weak and reactive layer of facets and spotty surface hoar. Yesterday skiers accidentally triggered a storm slab avalanche, partially burying a member of the group. Human triggering is likely.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Ski short pitches and regroup in safe spots.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 3

Wind Slabs

With ~80cm of light new snow available for transport, sustained SW winds will have loaded lee slopes. In windloaded areas, deeper slabs are expected to bond poorly to the facetted snow beneath it. Avoid slopes that have been loaded by wind.

Watch for signs of instability such as whumpfing, or cracking. Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 4

Loose Dry

Where the new snow is unconsolidated heavy sloughing is expected. In steep terrain these slides could entrain enough mass to be an issue for skiers and riders.

Be aware of party members below you that may be exposed to your sluffs.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 22nd, 2016 8:00AM