North Columbia

A bit of new snow will be adding to wind slab problems that have been developing since the storm. Slabs may not be as widespread as they were a few days ago, but they will require careful terrain management to avoid.

Moderate -

Monday night: Becoming cloudy with eventual scattered flurries bringing 3-7 of new snow. Light northwest winds.Tuesday: Cloudy with easing flurries and a trace of new snow, ending by midday.  Light northwest winds. Alpine high temperatures around -6 under a mild temperature inversion.Wednesday: Cloudy with increasing flurries bringing about 5 cm of new snow, increasing a bit overnight. Light to moderate southwest winds. Alpine high temperatures around -4.Thursday: Cloudy with continuing flurries bringing an uncertain 5-20 or more cm of new snow, continuing overnight. Alpine high temperatures reaching about -2 as freezing levels rise to 1800 metres.

Reports from Saturday and Sunday show an active couple of days for avalanches in the Columbias. A more notable MIN report from Saturday describes a large (size 2) snowmobile remote (from a distance) triggered storm slab in the Clemina Creek area. (link here) Numerous other small (size 1-1.5) storm slabs were also triggered with ski cutting and skier traffic. A notable outlier was a large (size 2.5) persistent slab release that was skier triggered below ridgecrest on a southwest aspect in the Connaught Creeek area in Glacier National Park.Prior to the storm, the last reported persistent slab activity was last Sunday when a few large (size 3) persistent slab avalanches were observed on south facing alpine features. This was the final report from a widespread persistent slab avalanche cycle that was quite active last week. The inability of our recent storm to produce a renewal of persistent slab activity suggests that this layer may finally have become dormant.Looking forward, expect a decrease in natural avalanche activity while the potential for human triggering sees a more gradual decline.

Saturday's storm brought about 30-40 cm of new snow to the region. Below the new snow interface, which appears for the most part to be free of any weak surface hoar crystals, 10 to 20 cm of older low density snow sits above old wind slabs in the alpine, and in some isolated areas above small surface hoar (feathery crystals). Avalanche activity on the 100-140 cm deep weak layer that formed during the dry spell in early December has greatly diminished over the last week. This layer is composed of weak facets, surface hoar, and a sun crust on steep south-facing slopes. It is believed to be trending toward a dormant state after the loading test brought by Saturday's storm failed to produce consistent reports of avalanches 'stepping down' to trigger it. Places that might still challenge this assumption of dormancy would be steep north and east facing slopes between 1900-2300 m and steep south-facing slopes in the alpine.The lower snowpack is generally strong and settled, with a crust that formed in late October near the bottom of the snowpack.