Avalanche Forecast

Issued: Jan 18th, 2018 5:00PM

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

Avalanche Canada cgarritty, Avalanche Canada

Give the new snow time to form a solid bond to the surface and remain especially cautious in wind affected terrain.

Summary

Confidence

Moderate -

Weather Forecast

Friday: Mainly cloudy. Light variable winds. Alpine high temperatures around -5.Saturday: Mainly cloudy with isolated flurries and a trace of new snow. Light to moderate southeast winds. Alpine high temperatures of -5.Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Moderate to strong east winds. Alpine high temperatures around -7.

Avalanche Summary

Reports from Wednesday include observations of thin (5 cm) storm slabs becoming highly reactive to skier traffic in the Howson Range, producing small remotely triggered (from a distance) and sympathetically triggered (by an adjacent release) slides. These small slabs were also running naturally in any terrain over a 37 degree incline.Reports from Monday included one remotely triggered Size 1 avalanche on a 50 cm deep surface hoar layer at 1000 m. Although small, this avalanche may be an indicator that the upper snowpack has settled into a more reactive slab.

Snowpack Summary

Snowfall from Wednesday and Thursday brought a variable 10-20 cm of new snow to the region. The new snow has buried a temperature crust left over from warm temperatures on the weekend. This crust likely exists well into the alpine. Beneath the crust, the same warm temperatures also worked to settle 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

Storm Slabs

An icon showing Storm Slabs
Thursday's new snow and south winds formed new storm slabs and some reports have indicated the new snow is not bonding well to the surface. Be extra cautious around steep rolls and in the lee of ridges and exposed terrain features.
Watch for signs of slab formation, like shooting cracks.Be conscious of wind loading patterns as you gain elevation.Use ridges or ribs to avoid steep pockets of wind loaded snow.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Jan 19th, 2018 2:00PM

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