Kootenay Boundary

A slab up to 100 cm in depth is consolidating above buried surface hoar which continues to produce large human triggered avalanches. Carefully plan and travel with intention to avoid convexities as well as steep open and/or sparsely treed slopes.

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This week will see a complete reversal in the weather pattern as warmer temperatures and dry conditions are expected to dominate. Warmer air aloft will begin to move into the province as an off shore upper ridge pushes inland and the flow aloft switches from cold northwesterly to mild southwesterly. With cold Arctic air trapped in the valleys of the eastern interior ranges the warm up will be painfully slow.TUESDAY: Mostly clear skies. Temperature inversion with below freezing air in the valley, above freezing (warmer) air between 2000 m and about 3000 m, light northwest wind, no snow expected.WEDNESAY: Scattered cloud, temperature inversion with below freezing air in the valley, above freezing (warmer) air between 1800 m and about 2500 m, light southwest wind, no snow expected.THURSAY: Broken cloud cover, temperature inversion with below freezing air in the valley, above freezing (warmer) air between 1500 m and about 2500 m, light southwest wind, no snow expected during the day, potential for very light rain/snow on Thursday night.

On Monday another avalanche failing on the mid-December interface was triggered remotely from 10 m away as a skier approached a rocky outcropping on an east/southeast facing feature around 1900 m. A skier also triggered a small storm slab on a west facing feature around 2200 m Monday which was suspected to have failed on the late December surface hoar. On Sunday a skier was involved in an avalanche on an east facing treeline feature at Kootenay Pass, the avalanche appears to have failed on the mid-December interface. On Saturday we received two reports of large avalanches failing on the mid-December interface. The first was initiated by explosive control work, the size 2.5 avalanche ran on a 35 to 40 degree slope that was southeast through southwest facing at treeline. The second avalanche was a size 3.0 that released naturally on a 30 degree east facing slope between 1900 and 1400 m. This crown was up to 75 cm in depth.

Two successive storms produced 25 to 50 cm of low density storm snow that was accompanied by moderate to strong winds out of the east, southeast, south and southwest. The new snow overlies 3 to 5 mm surface hoar, but we don't know much about the distribution of this weak layer yet.Between 60 and 100 cm below the surface you'll find the December 15th interface which consists of a melt-freeze crust on steep, solar, higher elevation slopes and well-developed surface hoar which seems most pronounced in sheltered terrain at and below treeline. The overlying slab is now deep and is gaining cohesion. This interface has hit the tipping point for human triggering as evidenced by recent avalanche activity listed above. Warming temperatures will likely make it more volatile on Tuesday. The lower snowpack is thought to be strong and well-settled.