Regions
Kootenay Boundary.
Wind slabs continue to be reactive to human triggers, especially on south-southwesterly aspects at treeline and above.
Confidence
High - The weather pattern is stable
Weather Forecast
Heading into March it feels more like January. The strengthening ridge will bring us another fairly long stretch of cold, dry and clear weather.SATURDAY/ SUNDAY/ MONDAY: Mostly sunny with treeline temperatures near -15. Moderate ridgetop wind from the East through the forecast period.
Avalanche Summary
On Thursday, dry loose sluffing was seen in steeper terrain features.
Snowpack Summary
An additional 15 cm accompanied by light southwest winds fell in Kootenay Pass and the Nelson area overnight. This adds an additional 20-30 cm of low density snow to the upper snowpack. This new snow may have a poor bond to the previous firm and faceted (sugary) snow surfaces. Old wind slabs from the strong northeast winds earlier this week continue to reactive to human triggers especially on southerly slopes. A buried surface hoar and crust interface that was buried on February 7th is now 30-50 cm deep. Two other surface hoar layers are buried 50 to 80 cm deep the snowpack (referred to as the February 1st and mid-January layers) these buried persistent weak layers remain reactive to human triggers. The snowpack is complex and requires diligence and patience. This MIN report reflects the Kootenay Pass area well. This MIN report reflects the Bonnigton Range.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
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.