Avalanche Forecast

Issued: Dec 1st, 2013 7:36AM

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

triley, Avalanche Canada

Purcells.

The storm is expected to bring more snow to the West and South of the region. New storm slabs are expected to be very easy to trigger during the storm and may run naturally in some parts of the region.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Overnight and Monday: 10-25 cm of snow overnight as the cold arctic air from the North meets the warm moist Pacific air crossing from the West. The West and South of the region should see the higher snowfall amounts. Freezing levels dropping to valley bottoms and winds becoming moderate from the Northeast by Monday afternoon.Tuesday: Cold and dry with light Northeast winds.Wednesday: Sunny with colder temperatures in the East and North of the region.

Avalanche Summary

New storm slabs are expected to develop overnight. Storm slab avalanches may be easily triggered where recently buried weak layers exist. The new load of storm snow, or storm slabs in motion may cause avalanches to release on this crust layer. The most likely place you would trigger this layer is on smooth, planar, north facing slopes.

Snowpack Summary

New storm slabs are developing above weak surface layers of facetted crystals and melt/freeze crusts. These recently buried weak layers may not support the new load of storm snow that is forecast. The deeply buried early season crust continues to be a concern. There have been reports of weak sugary crystals at the crust interface that may create an easy sliding surface and allow for wide propagations.

Problems

Storm Slabs

New storm slabs are developing. Forecast strong Westerly winds may cause these slabs to be very easy to trigger.

Minimize exposure during periods of heavy loading from new snow, wind.>The new snow may require several days to settle and stabilize due to the presence of newly buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

The added load from the new snow may overload the deeply buried weak layer of early season crust. Northerly aspects in the alpine are the most suspect areas for this crust to become reactive.

Storm slabs in motion may trigger deeper instabilities.>Be aware of the potential for large, deep avalanches due to the presence of a buried crust/ facet combo.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Dec 2nd, 2013 2:00PM