North Columbia

Lingering wind slabs are expected to be the main concern on Monday. Use extra caution in wind affected terrain.

Moderate - Wind effect is extremely variable

Mostly cloudy conditions are expected on Monday with sunny breaks in the north of the region. Alpine wind is expected to be light from the south in the morning switching to the north in the afternoon. Afternoon freezing levels are forecast to be around 800 m with treeline temperatures around -6C. A mix of sun and cloud is expected for Tuesday and Wednesday. Alpine wind is forecast to remain light from the north and treeline temperatures are expected to be around -10C.

On Saturday, skiers and snowmobilers triggered size 1 wind slabs and storm slabs.  These were 20-40 cm thick slabs.  Explosives also triggered a size 2 cornice which did not trigger a slab on the slope below and a size 1.5 loose dry avalanche.  On Friday, a natural size 3 storm slab avalanche was observed on a west aspect at 2500 m in the far north of the region. This occurred on a convex glacial feature and the slab was 80 cm thick. Other natural activity included a size 2.5 cornice release which triggered a 50 cm thick slab on a north aspect at 2400 m and loose wet avalanches from steep rocky sun exposed terrain below treeline. Skiers triggered storm slabs up to size 1.5 and explosives triggered storm slabs up size 3 on most aspects at treeline and in the alpine. On Wednesday and Thursday, widespread natural avalanches up to size 3 were being observed during the storm. On Monday, lingering wind slabs are expected to be the main concern. These should be expected in wind exposed terrain on aspects loaded by the recent southwest wind.

30-60 cm of recent storm snow typically overlies the variable mid-January interface with the largest snowfall amounts in the north of the region. The buried interface consists of wind affected surfaces in exposed terrain, surface hoar up to 10 mm in sheltered areas, and/or widespread faceted old snow. The bond between the new snow and the old surface is generally gaining strength with colder temperatures that followed the storm but weaknesses are lingering, especially where surface hoar is preserved. Strong southwest winds during the storm and moderate southwest winds following the storm have redistributed the new snow and developed wind slabs in leeward terrain features. The mid-December facet/surface hoar persistent weak layer can be found buried 100-120 cm deep. This layer is now dormant in many areas in the south of the region, but may still be a concern in shallow snowpack parts of the region and in the far north of the region in places like Clemina Creek. It is highly recommended to investigate this layer before committing to any large, unsupported features. The lower snowpack seems to be generally strong and well settled.