Archived

Avalanche Forecast

Mar 23rd, 2013–Mar 24th, 2013

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

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.

Avalanche 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