Avalanche Forecast

Issued: Dec 1st, 2013 7:37AM

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

Kootenay Boundary.

New snow and wind are increasing the avalanche danger. Storm slabs may release naturally or be triggered by light additional loads like skiers/riders.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Overnight and Monday: 15-30 cm of snow overnight as the cold arctic air from the North meets the warm moist Pacific air crossing from the West. The mountain passes in the South of the region may see higher snowfall amounts. Â Freezing levels dropping to valley bottoms and winds becoming moderate from the Northeast by Monday afternoon.Tuesday: Cold and dry with light Northerly winds.Wednesday: Sunny, dry and cold.

Avalanche Summary

The new storm snow is expected to release naturally or with light additionalÂ loads like skiers. Areas that have a deeply buried early season crust may experience a cycle of large avalanches due to the added load of the storm snow.

Snowpack Summary

New storm slabs are developing above recently buried weak layers of surface hoar on North aspects and melt/freeze crusts on solar aspects. The new snow may not bond well to these old weak surface layers. There are some reports of a deeply buried early season crust that formed in October. We do not know the extent of this layer with respect to aspect and areas within the region. In other regions of the interior mountains, this layer is more likely to be found in the high alpine on northerly aspects.

Problems

Storm Slabs

New storm slabs may release naturally or be triggered by light additional loads like skiers/riders. These storm slabs may be sitting on a layer of surface hoar on Northerly aspects, or on a melt/freeze crust on Southerly aspects.

Minimize exposure during periods of heavy loading from new snow, wind.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Persistent Slabs

I have this problem on all aspects, because we do not have many reports from this region. Dig down and find out if this deeply buried weak layer is in your area. Let us know what you find.

Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

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