Avalanche Forecast

Moderate -

Saturday night: Flurries bringing 5-10 cm of new snow. Moderate to strong southwest winds. Sunday: Cloudy with isolated flurries and a trace of new snow. Light to moderate southwest winds. Freezing level to 1600 metres with alpine temperatures of -2. Monday: Cloudy with scattered flurries bringing approximately 5 cm of new snow. Light to moderate southwest winds. Freezing level to 1900 metres with alpine temperatures around 0. Tuesday: Cloudy with scattered wet flurries bringing approximately 5 cm of new snow to higher elevations. Rain below about 1600 metres. Light to moderate south winds. Freezing level to 2000 metres with alpine temperatures around 0 or +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. Other relatively recent persistent slab avalanches include a remotely triggered a Size 2.5 slab that failed on the late-February surface hoar down 60 cm on Tuesday as well as an older report from the weekend that details a natural Size 3.5 deep persistent slab avalanche occurring in an alpine bowl in the Bonnington range. Its crown fracture was 200+ cm thick and the avalanche was described as a climax event.Looking forward, expect recently formed storm and wind slabs to remain reactive on Sunday. Also 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 65-100 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).