Regions
Kootenay Boundary.
A Special Public Avalanche Warning is in effect for this region. The snowpack remains primed for human-triggered avalanches, especially at higher elevations.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Sunday
Weather Forecast
SATURDAY Night: Mostly dry. Freezing level down to valley floor. Light southerly winds.SUNDAY: Between a trace and 10 cm new snow. Freezing level around 1000 m. Light southerly winds around treeline, high alpine elevations could see moderate southwest wind.MONDAY: 10-20 cm new snow. Freezing level around 1500 m. Moderate southwesterly winds.TUESDAY: Continued snow with another 10 to 20 cm. Freezing level around 1500 m. Moderate southwest winds.
Avalanche Summary
Avalanches up to size 2 were reported Friday, but fewer than earlier in the week; as expected natural avalanche activity appears to be tapering off. Avalanches were running either within the storm snow or at the bottom of the storm snow where surface hoar or faceted (sugary) snow formed during the Nov / Dec drought. Remotely or explosive triggered avalanches with 50 cm crowns, on NW to NE aspects, are evidence this layer remains active.
Snowpack Summary
Approximately 50 to 60 cm of snow has fell last week, with strong southerly winds. This snow sits on top of a weak layer of facets (sugary crystals), surface hoar (feathery crystals) and a sun crust on south aspects. Recent "sudden" snowpack test results and remotely triggered avalanches indicate it remains a critical layer that can release avalanches.Lower in the snowpack, previous weak layers appear inactive. These deeper layers could possibly cause problems on cold (north facing) slopes at high elevations where the snowpack is thin, but in most places, this is unlikely.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.