South Columbia

Avalanche activity has been at a steady peak and touchy conditions will persist.  Travel in avalanche terrain is not recommended.

High -

Thursday: Cloudy with flurries bringing 5-10 cm of new snow. Light southeast winds. Alpine high temperatures to -9.Friday: Mainly cloudy. Light west winds. Alpine high temperatures to -8.Saturday: Mainly cloudy with scattered isolated flurries bringing a trace to 5 cm of new snow. Light to moderate southwest winds. Alpine high temperatures to -1

Reports from Tuesday described 'electric' conditions in several areas in the South Columbias and suggest a high point in a natural avalanche cycle on both the January 5 surface hoar layer as well as the December 15 surface hoar layer. Avalanche activity on these interfaces was extensive, with natural and remote (from a distance) triggers forming a large percentage of observations. Sizes ranged from Size 1-3, slab depths ranged from 30-80 cm, and activity was observed on all aspects and elevation ranges. Reports from the previous two days showed similar activity.Looking forward, incremental loading from new snow on Thursday is likely to keep the region in an active pattern of avalanche activity that may intensify toward the weekend with forecast warming.Please share your recent observations through the Mountain Information Network (MIN).

Recent storms have brought 40-60 cm of new snow to the region. The new snow sits on surface hoar on sheltered slopes as well as sun crust on steep solar aspects. Numerous storm slab avalanches resulted as the new snow formed a slab before bonding to the surface. Moderate to strong southwest winds accompanied the snowfall at higher elevations, creating wind slabs in lee features.As the new snow continues to consolidate, it forms a dangerous slab above several persistent weak layers that exist in the snowpack. The first of these is the surface hoar that exists at the new snow interface. Recent snowpack tests and avalanche activity show a high degree of reactivity at this layer. Below it, the December 15 surface hoar is now buried 50 to 100 cm deep. This layer has been the failure plane in many recent destructive slab avalanches. Its reactivity has been most apparent at treeline and below treeline. Deeper in the snowpack at depths of about 90 to 150 cm, a rain crust from November is producing variable snowpack test results, from sudden fracture characters to no result. This layer is considered dormant but could be triggered in thin spots around variable snowpack areas in the alpine.