Avalanche Forecast

Issued: Jan 17th, 2018 4:49PM

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

cgarritty, Avalanche Canada

Northwest Inland.

New snow and wind are increasing avalanche danger in the region. Take a cautious approach while the new snow settles and bonds to the surface.

Summary

Confidence

Moderate -

Weather Forecast

Wednesday night: Cloudy with flurries bringing 3-7 cm of new snow. Moderate southeast winds.Thursday: Cloudy with continuing isolated flurries and a trace of new snow. Light to moderate southeast winds. Alpine high temperatures to -5.Friday: Mainly cloudy. Light southeast winds. Alpine high temperatures to -5.Saturday: Mainly cloudy with isolated flurries and a trace of new snow. Light to moderate southwest winds. Alpine high temperatures to -6.

Avalanche Summary

Reports from Monday include two small skier triggered avalanches (both size 1). One was a wind slab on a northwest-facing slope under a wind lip and the other was a remotely triggered avalanche on a 50 cm deep surface hoar layer at 1000 m. These small avalanches may be indicators that the upper snowpack has settled into a more reactive slab.

Snowpack Summary

New snow is falling on a temperature crust left over from warm temperatures on the weekend. This crust likely exists well into the alpine. The warm temperatures also settled the upper snowpack, potentially forming a slab above buried weak layers in the top 50 cm of the snowpack. The potential weak layers include a few crusts and surface hoar layers that formed in early January and December. Recent reports suggest the snow is well bonded to most of these layers, but the recent settlement of the upper snowpack may have changed that.

Problems

Wind Slabs

New snow will continue building fresh slabs over Wednesday night and it will also be burying old wind slabs. Be extra cautious around steep rolls and in the lee of ridges and exposed terrain features.

Use ridges or ribs to avoid steep pockets of wind loaded snow.Be conscious of wind loading patterns as you gain elevation.Watch for signs of wind slab formation, like shooting cracks.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

There are signs that suggest a reactive slab has finally developed above weak layers in the top 50 cm of the snowpack. It's still early to be certain, but persistent slab problems should be on your radar. Thin areas and convexities are most suspect.

Choose well supported terrain without convexities.Carefully evaluate and use extra caution around thin snowpack areas.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Jan 18th, 2018 2:00PM