The danger has come down, but large human triggered avalanches remain possible. Start with small test slopes and build up slowly to the bigger terrain features. There is still a lot of uncertainty associated with this early winter snowpack.
Summary
Confidence
Moderate
Weather Forecast
High pressure dominates the weather pattern for the next few days. The next major weather maker is not expected in the South Columbias until at least Friday. MONDAY: Trace of snow, freezing level near valley bottom, light NW wind. TUESDAY: No snow expected, freezing level at valley bottom, light NW wind. WEDNESDAY: No snow expected, freezing level at valley bottom, light NW wind.
Avalanche Summary
No new activity to report from Saturday. On Friday avalanche observations were limited to small cornice fall avalanches triggered by control work. On Thursday a very large natural avalanche was observed on a SE facing feature at 2000m that initially failed below ridge crest and ran full path. In the neighboring North Columbia's Thursday was a very active day with the following activity being reported: "A large natural avalanche cycle occurred on Thursday with several large natural avalanches to size 3 being reported on all aspects between 1300 and 2400m. A few smaller rider triggered avalanches were also reported in various drainages on NE facing slopes. One of the most interesting observations was of numerous avalanches to size 2.5 running on all aspects between 1400 and 1600m north of Revelstoke. These were likely running on the early December surface hoar."
Snowpack Summary
A string of storms between December 2nd and December 13th produced 80 to 130cm of storm snow in the South Columbias which is settling out at all elevations. You may find a brittle thin crust about 15 to 40cm below the snow surface as high as 1800m that was formed by rain and warm temperatures on December 8th. The early December persistent weak layer can be found down 70 to 120cm below the surface. This weak layer manifests as an old sun crust on due south facing features in the alpine, large grained surface hoar below 1800m and small facets in isolated pockets. The surface hoar has been the primary concern lately, especially below treeline between 1400m and 1800m. Recent test results on this interface have been widely variable. Sudden Planar, Resistant Planar and Sudden Collapse results have been reported as recently as Dec. 13th. All the variation in trigger sensitivity makes this layer tricky to manage. Recent winds out of the south, SW and most recently SE have formed wind slabs on lee features that are mainly confined to the alpine, but you may find the odd fresh wind slab at treeline too. The mid and lower portions of the snowpack are thought to be well settled.
ghelgeson,
Avalanche Canada
