Avalanche Forecast

Issued: Dec 11th, 2013 8:33AM

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

Thursday: Light snowfall / Moderate to strong westerly winds / Freezing level at valley bottomFriday: Flurries / Moderate northwesterly winds / Freezing level at 1000mSaturday: Light snowfall / Moderate southerly winds / Freezing level at 1000m

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. 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 significant propagation. 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 create new windslabs at higher elevations adding to an existing windslab problem. Watch for triggering in gullies and behind ridge crests.

Be cautious as you transition into wind affected terrain.>Avoid travelling in areas that have been reverse loaded by winds.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

A weak interface buried at the end of November is now buried by up to 70cm 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

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 12th, 2013 2:00PM