Archived

Avalanche Forecast

Jan 31st, 2013–Feb 1st, 2013

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Friday

Weather Forecast

Friday: Light W winds. Alpine temperature near 0. Thin cloud, with sunny breaks. No snow.Saturday: Light W winds. Alpine temperature near +2. Sunny skies, with valley cloud. No snow.Sunday: Moderate SW wind. Alpine temperature near -7. Light snow.

Avalanche Summary

Size 1 to 2 loose dry avalanches have been failing with natural and human triggers in steep terrain. Increasingly, human-triggered slabs (size 1 to 2) are failing on the Jan 23 interface. In many cases, these events have been on wind-loaded aspects.

Snowpack Summary

Recent NW winds have redistributed 15-40 cm of recent snow into soft or hard slabs on lee slopes in the alpine and at treeline. A weak interface buried on Jan 23 seems to be becoming more reactive as the slab above settles and becomes more cohesive. Deeper, about 50-60cm down, a weak interface buried in early January exhibits moderate to hard, sudden results in snowpack tests. The snowpack below this is generally well bonded. Forecast warming may increase the likelihood of triggering a persistent slab.

Avalanche Problems

Wind Slabs

Be alert for wind slabs behind terrain breaks such as ridges and ribs.

Be cautious as you transition into wind affected terrain.>Travel on ridgetops to avoid wind slabs on slopes below.>Avoid steep slopes below cornices.>

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

A mixed bag of weak interfaces is buried about 40 cm down. As temperatures rise, the likelihood of triggering a persistent slab may increase.

Avoid convexities or areas with a thin or variable snowpack.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 4