Avalanche Forecast

Issued: Dec 22nd, 2018 3:41PM

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

mconlan, Avalanche Canada

Kootenay Boundary.

A weak layer exists in our snowpack at a depth where humans can still trigger it. It is a good time to remain conservative with your terrain selection.

Summary

Confidence

High -

Weather Forecast

SATURDAY NIGHT: Cloudy with light snowfall, accumulation 5 to 10 cm, moderate to strong southwest winds, freezing level below valley bottom.SUNDAY: Cloudy with light snowfall, accumulation 5 cm, moderate southwest winds, alpine temperature -6 C, freezing level below valley bottom.MONDAY: Mostly cloudy, light southwest winds, alpine temperature -7 C, freezing level below valley bottom.TUESDAY: Mostly cloudy, light northwest winds, alpine temperature -9 C, freezing level below valley bottom.

Avalanche Summary

Large (size 2 to 3) slab avalanches were triggered by explosives on Friday. The avalanches were generally 10 to 40 cm deep and within recent storm snow. There was also further evidence of the natural avalanche cycle from Thursday.

Snowpack Summary

Strong winds from variable directions have redistributed the recent storm snow, producing wind slabs in lee terrain features on all aspects.Beneath this, around 50 to 100 cm of snow is poorly bonded to a rain crust and a weak layer of feathery surface hoar and sugary facets. Avalanche activity, remote triggering, and snowpack test results tell us that it is a critical layer. It is best to travel extremely cautiously with this layer in the snowpack.The lower snowpack is well-settled.

Problems

Persistent Slabs

A weak layer buried around 50 to 100 cm is the primary concern. Expect to find it on all aspects and all elevations, except for the most exposed of terrain where wind or sun may have altered it. This weak layer has recently produced large avalanches.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Choose low-angle terrain without overhead exposure and watch for clues of instability.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Recent strong winds from variable directions have produced touchy wind slabs in lee terrain features. Be cautious near ridges on all aspects.

If triggered, wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 23rd, 2018 2:00PM