Avalanche Forecast
Issued: Dec 20th, 2011 8:17AM
The alpine rating is Persistent Slabs and Wind Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Due to variable snopack conditions
Weather Forecast
Wednesday: Mostly dry. Light northerly winds. Alpine temperatures around -12C. Thursday: Dry. Winds becoming westerly. Remaining cold, but a mild inversion could locally elevate alpine temperatures by a few degrees. Friday: light snowfall with around 2 cm expected. Moderate NW winds. Alpine temperatures around -12C.
Avalanche Summary
A natural avalanche cycle up to size 2 occurred in the Dogtooth and Bugaboo ranges last weekend. Human-triggered slab avalanches have been reported subsequently from these areas up to size 2 on a variety of aspects and elevations. Due to the well-developed nature of the surface hoar layer, touchy avalanche conditions will persist where the slab is sufficiently deep and avalanches have not already run.
Snowpack Summary
The Purcell region has been getting less snow in the recent storms than the Selkirks. This means in many areas we have not reached critical threshold on a layer of large surface hoar and near surface facets that was buried mid-December. Exceptions to this are the Dogtooth range and Bugaboos, where avalanches to size 2 have been releasing on this layer with fracture depths of 20-30 cm. Typically, the mid-December surface hoar layer currently lies about 20 cm below the snow surface. Some areas have a sun crust in the alpine on steep south and west aspects. There is a rain crust that is buried between 40 to 55 cm in some areas that reaches up to about 2200 m. Lower in the snowpack, the mid-layers are well-consolidated and strong. Near the base of the snowpack there are a few layers that have the potential to wake up with a really big storm or very heavy loads. These include a surface hoar layer from early November, a crust/facet combo from October and the interface on steep glaciated terrain with snow that did not melt over the summer.
Problems
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 21st, 2011 8:00AM