Avalanche Forecast

Issued: Mar 23rd, 2013 9:28AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs, Cornices and Loose Wet.

jfloyer, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Good

Weather Forecast

Synopsis: Generally very fine weather with cool overnight temperatures and warm, sunny days.Sunday, Monday and Tuesday: Clear and sunny. Freezing level around 1600 m, becoming slightly higher each day. Light winds.

Avalanche Summary

On Friday, only small sluffs were observed. On Thursday, several size 1.5-2 avalanches were either deliberately ski-cut or accidentally triggered on a range of aspects at elevations from 1800 - 2100 m. All failures were on a crust, typically buried 20-40 cm deep. Explosive avalanche control produced similar results.

Snowpack Summary

Between 20 and 60 cm recent storm snow rests on a thick crust that exists up to ridge top. The bond between the storm snow and the crust was initially poor above 1800 m, but appears to have gained some strength. In some places, you may find an additional, thinner crust within the top 60 cm snow. A buried surface hoar layer lies buried approximately 80 cm below the surface and continues to fail in a sudden planar fashion when tested. However, in most places it is likely not a concern due to the thick supportive crust that lies above it. Potentially large fragile cornices loom over many slopes.

Problems

Storm Slabs

Snow has been reacting readily to human triggers on a buried crust around 40 cm below the surface.

Choose well supported terrain without convexities.>Avoid freshly wind loaded features.>If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.>Plan escape routes and identify safe zones before committing to your line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Cornices

With solar radiation and warm daytime temperatures, cornices will become unstable. There is a chance the weight of a cornice dropping onto the slope below could trigger an avalanche on the March 15th crust.

Do not travel on slopes that are exposed to cornices overhead.>Give cornices a wide berth when travelling on ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Loose Wet

Solar aspects are likely to see loose snow avalanches on solar aspects when the sun comes out and temperatures start to warm. There is a danger that surface avalanches may step down to pull out slabs on the buried crust.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Mar 24th, 2013 2:00PM