South Columbia

The trees are NOT a safe haven right now as a persistent weak layer at lower elevations is sensitive to human triggers. Increasing winds Saturday may form touchy wind slabs in the alpine too.

Low - Timing, track, or intensity of incoming weather system is uncertain on Sunday

We've reached the end of the high impact storm train. A rather mundane system drifts into the region Saturday night and then were looking at high pressure for at least a few days. SATURDAY: Trace of snow during the day. Freezing level holding around 700m. Winds expected to be light SW for most of the day, increasing to moderate SW in the afternoon. SATURDAY NIGHT: Freezing level 500m, moderate to strong SW winds, 3 to 20cm of snow. SUNDAY: Freezing level rising to 1200m. Moderate SW winds. 1 to 5cm of snow expected. MONDAY: No snow expected. Freezing level at valley bottom. Light NW winds.

Recent observations have been very limited, but I suspect that recent avalanche activity is far more widespread than the current data set would lead us to believe. 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."

A string of storms that began on December 2nd has produced 70 - 110cm of storm snow in the South Columbias. You may find a brittle crust about 20 cm below the snow surface as high as 2000m that was formed by rain and warm temperatures last Tuesday. Below all the new snow lies the early December persistent weak layer. This weak layer manifests as an old sun crust on due south facing features in the alpine, and large grained surface hoar below 1800m and small facets in isolated pockets. The surface hoar is the major player and it's been most reactive below treeline between 1400 and 1800m. Recent winds out of the southwest 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.