Avalanche Forecast

Issued: Dec 12th, 2013 8:21AM

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

jlammers, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Friday: Trace amounts of new snow / Light west winds / Freezing level at 1100mSaturday: Light snowfall / Strong west winds / Freezing level at 1100mSunday: Light snowfall / Moderate southwest winds / Freezing level at 1500m

Avalanche Summary

Small wind slab avalanches have been observed at treeline and in the alpine around Nelson and in the Kootenay Pass area.

Snowpack Summary

Dribs and drabs of recent snowfall now overlie generally faceted surfaces that formed during the recent cold snap. At the same buried interface you may find small surface hoar on sheltered slopes or windslabs in exposed alpine terrain. In some high elevation terrain the new snow may have been shifted into pockets of small windslabs.Between 50 and 70cm below the surface you may find a weak layer of surface hoar on sheltered north facing slopes and a crust on steep solar aspects. In some areas the overlying snowpack has not yet settled into a cohesive slab required for slab avalanche activity. There are reports of a deeply buried early season crust that formed in October, this layer is more likely to be found in the high alpine on northerly aspects. Little is known about its reactivity in this region.

Problems

Wind Slabs

Light amounts of new snow and wind may have created thin new windslabs at high alpine elevations adding to an existing windslab problem. Watch for triggering in gullies and behind ridge crests.

Avoid travelling in areas that have been reverse loaded by winds.>Be cautious as you transition into wind affected terrain.>The recent snow may now be hiding windslabs that were easily visible before the snow fell.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

A weak interface buried at the end of November is now buried by up to 60cm of snow. Triggering this layer may be more likely in steep, unsupported terrain, and in areas where the overlying snow has settled into a cohesive slab

Dig down to find and test weak layers before committing to a line.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 13th, 2013 2:00PM