Avalanche Forecast

Issued: Dec 23rd, 2018 4:15PM

The alpine rating is moderate, 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 lingers in our snowpack. It is a good time to remain conservative with your terrain selection. See this forecaster's blog, which describes this persistent problem: www.avalanche.ca/blogs/persistent-slab

Summary

Confidence

High.

Weather Forecast

SUNDAY NIGHT: Mostly cloudy, freezing level 600 m.MONDAY: Partly cloudy, light southwest winds, alpine temperature -8Â°c, freezing level 900 m. TUESDAY: Partly cloudy, light northwest winds, alpine temperature -9Â°c, freezing level below valley bottom. WEDNESDAY: Mostly cloudy, light southwest winds, alpine temperature -11Â°c, freezing level below valley bottom.

Avalanche Summary

A few small (size 1) wind slab avalanches were observed at high elevations on Saturday. 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 and Friday.

Snowpack Summary

Strong winds have redistributed the recent storm snow, producing wind slabs in lee terrain features. These slabs likely wont bond well to underlying surfaces.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 remain conservative and travel 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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Wind slabs may linger from previous storms. Be cautious in terrain features adjacent to ridges.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 24th, 2018 2:00PM