Kootenay Boundary

Watch for signs of slabs on all aspects in wind exposed terrain. Moderate to strong outflow winds are expected to cause reverse loading on Tuesday. Use extra caution on steep sun exposed slopes in the afternoon.

Moderate - Wind speed and direction is uncertain

Mostly cloudy conditions are expected Tuesday morning with the possibility of lingering flurries. Mostly sunny conditions are expected by Tuesday afternoon. Treeline temperatures are expected to fall to around -20C and alpine winds are forecast to be moderate to strong from the north. Sunny conditions are expected for Wednesday and Thursday with treeline temperatures around -15C during the afternoon and -25C overnight. Alpine winds are forecast to be light from the northeast on Wednesday and moderate from the northwest on Thursday.

Early reports from Monday include two natural size 2 storm slabs on southern aspects at 1850-2000m elevation. Explosives triggered several more storm slabs up to size 2.5 in the same terrain. This activity was limited to the new snow sliding on the old snow surface and wind loading may have contributed to the slab formation. On Sunday, a skier triggered a small size 1 wind slab avalanche on an isolated ridge top feature. On Tuesday, recently formed wind slabs are expected to remain reactive to human triggering. Ongoing wind loading is also expected on Tuesday with the forecast for moderate to strong northerly winds in the alpine. With the winds switching directions, wind slabs should be expected on a variety of aspects.

10-20 cm of new snow has buried a highly variable old snow surface. This interface consists of wind scoured surfaces and old wind slabs in exposed terrain, widespread near surface faceting, surface hoar in sheltered terrain, and/or a breakable sun crust on steep solar aspects. Recent moderate to strong winds from a variety of directions is expected to have redistributed this new snow in wind exposed terrain. In the upper snowpack below the new storm snow, a couple old freezing rain crusts may exist. The mid-December surface hoar layer sits down 50-80 cm. This layer is still reactive to snowpack tests in some areas but is generally considered to be dormant. Below this layer, the snowpack is generally well settled and stable.