Avalanche Forecast

Issued: Dec 4th, 2013 8:46AM

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

triley, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Mostly clear and cold for the forecast period. There is a chance of some cloud and very light flurries in the Southeast.

Avalanche Summary

No reports of natural avalanches releasing after the storm. Storm slab avalanches may continue to be triggered by light additional loads like skiing/riding. Storm slab avalanches that are released may be large and destructive. This storm needs some time to settle and bond, forecast cold temperatures may preserve recently buried weak layers and require more time to settle and bond than when the post storm temperatures are warm. This is a complex avalanche forecasting scenario; complicated by early season timing when we have few observations coming from the field.

Snowpack Summary

The new storm slab is about 40-70 cm deep depending on where you are in the region. Storm slabs are sitting above recently buried weak layers of surface hoar on North aspects and melt/freeze crusts on solar aspects. In some parts of the region, the storm slab may not be well consolidated and may not result in shears from snow-pit tests. There are some reports of a deeply buried early season crust that formed in October, this layer is more likely to be found in the high alpine on northerly aspects.

Problems

Wind Slabs

Northeast winds have created wind slabs at higher elevations. Wind slabs may have reverse loaded terrain features that were stripped by Westerly winds during the recent storm.

Be cautious as you transition into wind affected terrain.>Be careful with wind loaded pockets. Be aware of wide variation in snowpack depth>

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

We expect the recent storm snow to continue to be reactive where it sits above surface hoar and crusts that were buried at the end of November.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Dec 5th, 2013 2:00PM