Regions
Kootenay Boundary.
A Special Public Avalanche Warning is in effect for this region. Continued warm temperatures and sunshine are expected to maintain elevated avalanche danger.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Monday
Weather Forecast
Monday: A mix of sun and cloud with warm air remaining at higher elevations and cold air remaining in the valleys. Freezing level 3000m. Light southeasterly winds.Tuesday: Cloud increasing. Light rain or snow in the afternoon, 2-4 mm. Freezing level dropping from around 2500m in the morning to around 1800m in the afternoon. Moderate southerly winds.Wednesday: Light snow, around 5 cm, increasing in the evening. Freezing level around 1400m. Moderate southerly winds.
Avalanche Summary
Very significant avalanche activity occurred in the region last Wednesday and Thursday. A smaller avalanche cycle, mostly affecting the recent storm snow was reported on Saturday. While the weather remains warm, there is still an increased likelihood of triggering something large.
Snowpack Summary
Warm alpine temperatures have made the snow surface moist on slopes that face the sun. Below the surface, 40 to 60 cm of recent snow has settling into a cohesive slab on top of the reactive January 5th interface which consists of a crust/surface hoar combination on steep southerly aspects and pure surface hoar on remaining aspects. The late December surface hoar also remains reactive and is now down 50 to 90 cm below the surface. Adding to the complexity of the mid to upper snowpack is the mid-December surface hoar which is now 60 to 120 cm below the surface. This spooky interface continues to produce sudden snowpack test results and is most pronounced at treeline, but is also present below treeline. The overlying slab is now deep, dense and destructive. Two laminated crusts created by rain events in late November lay just below the mid-December interface, and may co-exist with facets. In shallow, rocky terrain the mid-December surface hoar and the late November crust seem to be reacting together which is a volatile combination.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.