Kootenay Boundary

New snow, intense winds, and rising freezing levels will be a recipe for touchy conditions and HIGH avalanche danger on Friday.

Moderate - Forecast snowfall amounts are uncertain on Friday

Thursday night: Flurries bringing 10-15 cm of new snow. Moderate to strong southwest winds. Friday: Continuing flurries bringing approximately 10 cm of new snow. Strong to extreme southwest winds. Freezing level to 1600 metres with alpine temperatures of -1. Saturday: Flurries bringing another 5-10 cm of new snow, beginning in the afternoon. Moderate to strong south winds, gusting to extreme. Freezing level to 1600 metres with alpine temperatures of -1. Sunday: Cloudy with scattered flurries bringing approximately 5 cm of new snow. Moderate southwest winds. Freezing level to 1600 metres with alpine temperatures of -1.

Reports from Wednesday include observations of numerous explosives control results generating storm slab releases from Size 1.5-2. These occurred on a range of aspects at treeline and above and featured crown fractures averaging around 20 cm. On Tuesday, a natural Size 1.5 storm slab was observed on a north aspect at 1950 m. A skier also remotely triggered a Size 2.5 slab avalanche from 5 m away on a north aspect at 2125 m, failing on the late-February surface hoar down 60 cm. An older report from the weekend remains notable for detailing a natural Size 3.5 deep persistent slab avalanche occurring in an alpine bowl in the Bonnington range on west and northwest aspects at 2300 m elevation. The crown line was 200+ cm thick and it was described as a climax event.Looking forward, expect fresh, touchy storm slabs in the mountains on Friday and keep in mind the touchy wind slabs that existed beneath them just the day before. Large persistent slab avalanches remain a concern and it may be possible for a person to directly trigger a persistent slab, or a smaller avalanche could step down. This will increase in likelihood as forecast snowfall and wind add load to the snowpack.

Another 15-20 cm over Tuesday and Wednesday has brought the typical storm accumulation in the past week to 55-85 cm. This snow has settled into a slab that sits over the late-February interface which includes sun crust, surface hoar, and weak faceted snow. Moderate to strong southwest wind over Tuesday night redistributed the most recent storm snow, forming new wind slabs in leeward terrain at higher elevations. The thick mid-February crust layer is now down 80-120 cm and exists on solar aspects and at lower elevations. This layer appears to have gone dormant but is still a concern which could wake up in the future with heavy loading or a major warming event. In most deeper snowpack areas, the snowpack is generally well settled and stable below this crust layer. However, some areas have a lingering basal weakness at the bottom of the snowpack. This is especially prevalent in shallow snowpack areas (less than ~150 cm).