Avalanche Forecast

Issued: Dec 6th, 2014 8:01AM

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

triley, Avalanche Canada

South Rockies.

We do not have much information from this region. If you have been out in the mountains, please send your observations to forecaster@avalanche.ca

Summary

Confidence

Poor - Due to the number and quality of field observations

Weather Forecast

An upper trough has been moving from Northwest to Southeast across the interior ranges today. This trough is expected to exit into the prairies overnight after leaving about 5-10 mm of precipitation. The precipitation should be snow to the valley bottoms at the beginning of the storm and become rain or freezing rain up to about 1500 metres. A ridge of high pressure will move in behind the trough bringing gradual clearing and cooler air for Sunday. The next system is forecast to move onto the South coast from the Southwest on Monday. This system looks wet for the lower mainland, but so far models do not show it pushing very much moisture into the interior. Areas in the South along the US border, and the Southeast corner near Fernie may get the most out of this system, but so far that is only expected to be 5- 10 mm of rain at lower elevations, or about 5-15 cm of snow at higher elevations. The Southwest flow looks like it will become more intense on Tuesday; warm, wet, and windy is the word so far, stay tuned for more info.

Avalanche Summary

No avalanche activity reported. Have you seen anything recently?

Snowpack Summary

There is at least one, maybe more, problematic layers in the South Rockies snowpack. Last weekends 30 - 60cm of storm snow buried a weak layer of facets over a crust which formed during November's dry spell. That interface is probably around a meter down now. Not much is known about the reactivity of this layer, nor the slab above it. But, it doesn't take much of a leap of faith to understand that a meter deep slab sitting on a persistent weak layer is a potentially bad thing.

Problems

Wind Slabs

Strong winds have developed windslabs in the alpine and at treeline in areas with snow available for transport. Forecast new snow may develop a new storm slab above these windslabs.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

A deeply buried crust with a weak layer of facets or surface hoar at the interface may exist in some parts of this region. Dig down and locate the crust, and then test how the upper snowpack is bonding to the crust.

Avoid spots where you're more likely to trigger large avalanches: thin spots, rock out-croppings, convex rollers and broad planar slopes without anchors like trees.>Every avalanche has the potential to step down to the ground right now, you need to manage your behavior and terrain use to account for that possibility.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Dec 7th, 2014 2:00PM