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Avalanche Forecast

Archived

Dec 5th, 2014–Dec 6th, 2014

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Columbia.

Avalanche danger has improved since last weekend, but a skier or sledder could still trigger a large avalanche in specific terrain.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Saturday: Light snow. Light to moderate SW winds. A layer of warm air may form at mountain height, while the valleys remain cooler.Sunday: Light snow. Light to moderate SW winds. The layer of warm air aloft may persist. Monday: Light snow. Light to moderate SW winds. Warming up at all elevations late in the day.

Avalanche Summary

Two recent slabs were observed in the far south of the region. These appear to have failed on a hard crust layer buried about a metre down. In general, avalanche activity has eased but there is still the chance of triggering a large avalanche on a persistent weak layer.

Snowpack Summary

Surface: Friday's light snow hides surfaces including wind slabs (variable in distribution); surface hoar, which has grown large in sheltered spots; and sun crusts on steep south-facing slopes.Upper-mid pack: Anywhere from 5-30 cm of settling snow sits on a crust which formed in late November. This crust is supportive above about 1800m, but is breaking down at lower elevations. About 1m down, a weak layer of surface hoar and/or facets can be found in some locations. Snowpack tests on this layer are showing improving results, but in some locations "pops and drops" indicate this beast could still be touchy.Lower pack: A thick rain crust from early November is buried over a metre down.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.