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Avalanche Forecast

Archived

Dec 20th, 2012–Dec 21st, 2012

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

Regions

Jasper.

Best ski conditions will be found at and below tree line on sheltered slopes.

Weather Forecast

An arctic cold front will move into the forecast area.  Light to moderate Southerly winds are forecast with the possibility of light flurries overnight, clearing by Friday.  Temperatures will be about 10 degrees colder than average for this time of year.

Snowpack Summary

Windslabs in the alpine are the primary avalanche concern. These are more likely to be encountered in the Columbia Icefields area where the strongest winds have been observed. In the Marmot Pass area on December 18th, surface slabs  failed with a moderate shear near treeline elevations. The mid snowpack remains supportive for the time being.

Avalanche Summary

No new avalanches have been observed.

Confidence

The weather pattern is stable

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.