Current conditions a concern
There are a few times during the winter to really watch it. Now is one of them. A persistent weak layer of surface hoar in the snowpack is unstable and has the capability of releasing large avalanches. This instability will probably linger in the snowpack for sometime.
Terrain to Watch:
It is critical to avoid open slopes steeper than about 30 degrees at treeline and below treeline. There is a very good chance of triggering an avalanche in this type of terrain. Be especially careful in cutblocks, where surface hoar is often prevelant and very unstable.
Techniques for managing hazard:
Plan trips with an extra margin of safety. Give yourself an ace card and choose terrain with lots of options to avoid steep open slopes and terrain traps. Be cautious while traveling under steep and open terrain. Triggering an avalanche from below is a distinct possibility.
A soft slab 40 - 60 cm thick overlies the Dec 29 surface hoar and suncrust layer. The surface hoar is patchy in distribution at treeline and widespread below treeline. It is most prevalent in north and east facing glades. On southerly facing slopes a sun crust exists at this interface. In places surface hoar probably rests on the crust. Given the nature of this layer, expect easy to moderate stability test results with a sudden planar shear. Additionally, expect propagation tests to indicate this layer will propagate if a fracture is initiated. If you don't see these results, I wouldn't assume it is safe.
Below the surface hoar are old rounding facets that are probably gaining strength. The lower snowpack is strong.
Prepared by Greg Johnson