Regions
Kootenay Boundary.
Travel in avalanche terrain is not recommended. Larger avalanches from above may run to valley bottoms, especially from sun exposed slopes.
Weather Forecast
Warm temperatures persist through the forecast period. WEDNESDAY: A mix of sun and cloud with alpine temperatures holding at + 8 degrees. Ridgetop winds light from the southeast and freezing levels 3300 m. THURSDAY: A mix of sun and cloud Alpine temperatures +7 degrees with freezing levels 3200 m. Ridgetop winds light from the southeast. FRIDAY: Cloudy with some sunny periods. Alpine temperatures near +8 degrees and freezing levels dropping to 3000 m. Ridgetop winds light from the East.
Avalanche Summary
On Monday, natural loose wet avalanches up to size 2 were reported from the region. These avalanches failed on all solar aspects (East through West) between 1600 to 2300 m. Some larger wet slab avalanches up to size 3 were also reported and triggered by explosives on southeast to southwest aspects between 1900-2200 m. Continued warming and a lack of overnight re-freeze we expect to see natural avalanche activity to continue on all aspects and elevations.
Snowpack Summary
Currently, solar aspects are showing signs of melt by day and a freeze by night. In some locations, sheltered northerly aspects have new surface hoar forming and variable wind effect remains on exposed slopes at treeline and in the alpine. The current snowpack is complex and with the continued warming and little overnight re-freeze the snowpack will continue to break down. The bigger questions are deeper in the snowpack. Two crusts exist in the upper snowpack and the bond of the overlying snow is most concerning with deteriorating. The first crust is down 20 to 30 cm and loose wet avalanches have slid on this interface. The deeper one down 60-95 cm has also been producing easy shears in test profiles and potentially just waiting for enough heat to penetrate and deteriorate before avalanches start failing on it, if they do? Its hard to say how many hot days and warm nights it will it take to wake up the more deeply buried weak layers.
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.