Avalanche Forecast

Issued: Nov 27th, 2012 9:30AM

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

ccampbell, Avalanche Canada

South Coast.

Avalanche danger is set to rise with stormy weather.

Summary

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

Wednesday: Snow with 5-15cm of accumulation, freezing levels around 1700m, and moderate to strong southerly winds. Thursday: Snow with 20-30cm of accumulation, freezing levels around 1500m, and strong southerly winds. Friday: Continued snowfall with another 15-20cm, freezing levels remaining at 1500m, and extreme southerly winds.

Avalanche Summary

Check out Wayne Flann's Avalanche Blog for a photo of a recent large avalanche off the north face of Mt. Currie. After a brief lull, avalanche activity will likely pick up again with forecast wind and snow.

Snowpack Summary

The snow surface consists of large surface hoar, a thin sun crust, surface facets, moist snow, or preserved storm snow depending on elevation, sun and wind exposure, slope angle, time of day, and aspect; all of which could become weak layers once buried by a sufficiently cohesive slab. The main snowpack feature is a rain crust buried early November and now down around 60-80cm at treeline. A weak layer of facets sitting on top of this crust shows "sudden" fracture character and the ability to propagate into large avalanches if triggered, but because this weakness is so close to the ground in most areas, associated avalanche activity will likely be limited to slopes with smooth ground cover (e.g. scree slopes, rock slabs, summer firn, glaciers, etc.). For more information check out the telemarktips.com forum, the Mountain Conditions Report, and Wayne Flann's Avalanche Blog.

Problems

Wind Slabs

Expect to find weak wind slabs below ridgecrests, behind terrain features, and in cross-loaded gullies. Natural avalanche activity is possible with heavy loading from snow and wind, and human triggering is likely, especially on steep convex slopes.

Assess start zones carefully and use safe travel techniques.>Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Slopes with smooth ground cover and reloaded bed surfaces. Prone to remote triggering and step down avalanches. Typical trigger points include thin rocky areas. May be difficult to trigger, but often very large with serious consequences.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of thin areas that may propagate to deeper instabilites.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Nov 28th, 2012 2:00PM