Avalanche Forecast

Issued: Jan 31st, 2013 9:25AM

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

pgoddard, Avalanche Canada

Kootenay Boundary.

Summary

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.

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

Valid until: Feb 1st, 2013 2:00PM