North Columbia

Very dangerous avalanche conditions exist in the Columbias. The situation will likely get worse before it gets better. Travel in avalanche terrain is not recommended. A Special Public Avalanche Warning is in effect in this region.

High -

Friday night: Flurries bringing 5-10 cm of new snow. Light southwest winds.Saturday: Cloudy with continuing isolated flurries and a trace of new snow. Light southwest winds. Alpine high temperatures to -4, rising overnight.Sunday: A mix of sun and cloud with thicker valley cloud due to a temperature inversion. Light variable winds. Freezing level rising to 1700 metres with alpine high temperatures to +1. Cooler at lower elevations.Monday: A mix of sun and cloud with thicker valley cloud due to lingering temperature inversion. Light southeast winds. Freezing level to 1700 metres with alpine temperatures to +3. Cooler at lower elevations.

Reports from Thursday show a continuation of recent heightened avalanche activity involving both storm slabs above the January 5 surface hoar layer and, to a somewhat lesser extent, the deeper December 15 surface hoar. Avalanche activity on these interfaces continues to be extensive, with natural and remote (from a distance) triggers forming a large percentage of observations. Sizes have ranged from Size 1-3, slab depths have generally ranged from 40-80 cm, and activity is being observed on all aspects and elevation ranges. Deeper releases on the December 15 layer have been focused around treeline and below. Reports from the previous two days showed similar activity.Some of the notable themes that are emerging from recent activity include accidental and remote triggering, 'step down' release types, releases on surprisingly low angle, supported terrain, and wide fracture propagations.Looking forward, expect a continuation of heightened human triggering potential that will likely increase over the weekend with forecast warming.

Recent storms have brought 40-70 cm of new snow to the region. This storm snow sits on surface hoar on sheltered slopes as well as sun crust on steep solar aspects. Numerous storm slab avalanches have resulted as the new snow formed a slab before bonding to the surface. Moderate to strong southerly winds accelerated this slab formation at higher elevations.As the new snow continues to consolidate, it progressively forms a dangerous slab above a number of persistent weak layers that exist in the snowpack. The first of these is the (January 5) surface hoar that covered the old snow surface. Recent snowpack tests and avalanche activity show high 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, with many of these 'stepping down' to this layer from shallower releases. This layer has been the most reactive at treeline and below.Deeper in the snowpack, down about 90 to 150 cm, a rain crust from November has shown less reactivity in recent snowpack tests. It is considered dormant but could be triggered in thin spots around variable snowpack areas in the alpine.