Kootenay Boundary

Persistent slab problems are being tested under a pattern of incremental loading coupled with warm daytime temperatures. Don't lose sight of the hazard lurking below the new snow.

Saturday: Flurries bringing 10-15 cm of new snow. Moderate to strong southwest winds. Freezing level to 1600 metres with alpine temperatures of -1. Sunday: Cloudy with scattered flurries bringing approximately 5 cm of new snow, mainly in the afternoon. Moderate southwest winds. Freezing level to 1600 metres with alpine temperatures of -1. Monday: Cloudy with scattered flurries bringing up to 5 cm of new snow. Light to moderate southwest winds. Freezing level to 2000 metres with alpine temperatures around 0.

Moderate -

Reports from Thursday highlight loose snow releases to Size 1 from steep terrain as well as more isolated Size 1 wind slabs reactive to ski cutting. 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 skier 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 recently formed storm and wind slabs to remain reactive on Saturday and for stability to deteriorate with forecast wind and new snow. Also keep in mind that large persistent slab avalanches remain an ongoing concern and it may be possible for a person to directly trigger a persistent slab, or for a smaller avalanche to step down.

Another 10-15 cm over Tuesday and Wednesday has brought typical storm accumulations from the past week to 65-100 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. Recent and ongoing moderate to strong southwest winds have redistributed much of the recent storm snow into touchy storm and wind slabs in leeward terrain, particularly at higher elevations. The thick mid-February crust layer is now down 90-135 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 ~200 cm).