Avalanche Forecast

Issued: Dec 9th, 2014 8:18AM

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

jlammers, Avalanche Canada

Kootenay Boundary.

Rain and warm temperatures will have a destabilizing effect on the snowpack. Watch your overhead hazard as weak layers may "wake-up" with the potential for large avalanches.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

A series of sub-tropical systems will make their way through the region on Wednesday and Thursday bringing moderate to locally heavy precipitation, freezing levels to about 2400m and strong southwest winds. By Friday, precipitation should taper-off dramatically with light snowfall, light southwest winds and freezing levels hovering at about 1500m.

Avalanche Summary

Numerous size 1 loose wet avalanches were observed in the Kootenay Pass area on Tuesday. Although observations have been limited, I suspect this activity has been fairly widespread. Rain may also spark destructive avalanche activity on persistent weaknesses which exist near the base of the snowpack. If you have any avalanche observations, please share them on our new Mountain Information Network. For more details, go to: http://www.avalanche.ca/blogs/VIYBuScAAJdbdqPz/m-i-n-intro

Snowpack Summary

Rain has likely saturated and weakened the upper snowpack in most areas. The extent of saturation will depend on elevation and the amount of rain that fell. At upper elevations, precipitation may have fallen as moist snow, and may be adding load and cohesion to a storm slab which overlies a weak layer of facets, surface hoar, a hard rain crust or a combination thereof. This storm slab has given easy results from light forces in snow profile tests. Near the base of the snowpack is a crust/facet combination which is more of a concern in the north of the region. This destructive layer continues to produce whumpfing, and may see a "wake-up" with warming and the load from rain or snow.

Problems

Persistent Slabs

Warm temperatures and the load from rain may spark renewed destructive avalanche activity on weak layers near the base of the snowpack. These weak layers can surprise with nasty consequences. Wet slabs are also a concern at all elevations.

Avoid large alpine features that may result in wide propagations if an avalanche steps down to the deeply buried crust.>Stick to low angle terrain if the snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 5

Loose Wet

Rain may trigger a round of pushy loose wet avalanche activity, especially in areas where loose snow overrides a hard crust. If precipitation falls as snow, dense and reactive storm slabs may form.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be cautious of wet sluffing in steep terrain.>At higher elevations, be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Dec 10th, 2014 2:00PM