Kootenay Boundary

We're in a holding pattern as persistent slab problems are tested by incremental loading and warm daytime temperatures. Don't lose sight of the hazard lurking below the new snow.

Moderate -

Monday: Flurries bringing up to 5 cm of new snow, rain below about 1300 metres. Light to moderate southwest winds. Freezing level to 1700 metres with alpine temperatures of -1. Tuesday: Flurries bringing up to 5 cm of new snow to high elevations, rain below about 1700 metres, intensifying overnight to rain at ridgetop. Light south winds. Freezing level rising to 2100 metres over the day with alpine temperatures of -1 to 0. Wednesday: Continuing high elevation flurries and lower elevation rain showers. Possible 15 cm accumulating in the alpine. Moderate to strong southwest winds. Freezing level dropping from 2000 metres in the afternoon. Alpine temperatures of 0 to -1.

Reports from Friday include numerous observations of storm slab avalanches from Size 1-2 throughout the region. Many of these were explosives controlled, but a number of the larger (Size 1.5-2) examples were naturally triggered. All but south aspects saw recent activity. Another notable report details a persistent slab that released with a very large vehicle controlled cornice trigger. The failure plane is uncertain but the slide ran full path, Size 3, on a north aspect. Two other large (Size 2.5-3.5) persistent slab avalanches were reported earlier last week.Looking forward, expect another light snowfall coupled with moderate to strong winds and warm temperatures to maintain touchy conditions on Monday. Keep in mind that large persistent slab avalanches are 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.

A week of stormy weather has brought 70-120 cm of recent snow to the region. Recent 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. Aside from wind effect, time and warming temperatures have allowed the storm snow to settle into a slab that sits over the late-February interface. This layer is composed of sun crust, surface hoar, and weak faceted snow. 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 being tracked for its potential to be woken up by the warming event forecast for early next week. 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).