Avalanche Forecast

Issued: Nov 26th, 2013 8:20AM

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

Avalanche Canada jfloyer, Avalanche Canada

If you've been out in the mountains recently, please help improve these forecasts by telling us what you see. Send a email to: forecaster@avalanche.ca.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

The dominant high pressure system slowly gives way to a weak Pacific frontal system that is expected to stay mostly to the north of this region. Flurries are possible, but expect little in the way of snow accumulation. Alpine temperatures will feel significantly colder than of late as the inversion that has been keeping things warm comes to an end on Wednesday.Wednesday: Dry. Light southwesterly winds. Freezing level around 500 m.Thursday: Flurries possible. Southwest ridgetop winds to 40 km/h. Freezing level around 400 m.Friday: Flurries possible. Light westerly winds. Freezing level lowering to around 700 m.

Avalanche Summary

No recent avalanche activity has been reported.

Snowpack Summary

Snowpack depths at treeline are approximately 70-100 cm. Alpine conditions are highly variable due to earlier redistribution of snow by strong winds. Probably the most important layer we've heard about in this region is a crust near the base of the snowpack that has sugary facets associated with it. In mid November, several large avalanches were reported on this weakness. We haven't heard recent reports, which likely means the layer is gaining strength, but bear in mind, not that many people are out there yet, and facets take a long time and a lot of snowpack load to properly heal. The most likely place you'd trigger this layer is on smooth, planar, north facing slopes, especially if the snowpack is unusually shallow in that area.A surface hoar layer has been identified at other locations in the Columbia ranges between 60and 120 cm from the surface and appears to be drainage specific. So far it's not been reported in the Purcells. If you've found it, please let us know.Recent temperature fluctuations, with little or no snow in the past week, mean you'll likely encounter a variety of snow surfaces, such as crusts, old wind slabs and shimmering surface hoar.

Problems

Persistent Slabs

An icon showing Persistent Slabs
The most important layer is a crust with sugary facets that lies 5-40 cm off the ground. The most likely place to trigger it would be on a smooth, planar slope on a northerly aspect in a shallow snowpack area.
Be aware of the potential for large, deep avalanches due to the presence of buried crust/ facet combo.>If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Nov 27th, 2013 2:00PM