Avalanche Forecast

Issued: Jan 11th, 2015 8:47AM

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

jlammers, Avalanche Canada

Kootenay Boundary.

Check out this great video blog post which describes conditions in the Nelson area: http://backcountryskiingcanada.com/forums/view/safety-talk/avalanche-conditions-report-video-1

Summary

Confidence

Good

Weather Forecast

A dry ridge of high pressure will dominate the region for the period. Valley cloud should develop for most days, although generally clear skies are expected at higher elevations. Winds are forecast to remain light from the northwest, while freezing levels should hover at (or near) valley bottom.

Avalanche Summary

On Saturday, skiers triggered numerous persistent slab avalanches to size 2 in the north of the region, in some cases remotely from a distance of 10m. With the stable weather pattern, recent storm instabilities should become much less reactive; however, I would expect ongoing skier-triggered avalanche activity on the December persistent weak layers.

Snowpack Summary

A dusting of low-density snow overlies well-developed surface hoar which sits above a melt-freeze crust. The crust is reported to exist on all aspects below about 1900m, and on steep solar aspects at higher elevations. Stubborn wind slabs are likely in exposed alpine and treeline terrain. The main snowpack concern is a buried surface hoar layer (down 60-120 cm), which is sitting on a hard rain crust in some places. This widespread persistent weakness, which formed in December, exists at all elevation bands and remains a concern for triggering.

Problems

Persistent Slabs

Continued skier-triggered avalanche activity is a clear indication that weak layers, buried up to 120cm below the surface, have not gone away. I'd remain conservative in my terrain selection, and exercise cautious group management.

Choose conservative lines and watch for clues of instability.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Wind Slabs

Storm accumulations from last week have likely gained considerable strength. That said, lingering wind slabs may still exist in the lee of ridge crests and terrain breaks.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Jan 12th, 2015 2:00PM