Regions
Kootenay Boundary.
Persistent hot and sunny weather is driving the avalanche danger. Avoid avalanche terrain especially in the afternoon on sunny slopes when the danger is at its HIGHEST.
Weather Forecast
THURSDAY: A mix of sun and cloud. Freezing levels 3200 m and alpine temperatures near +9 degrees. Ridgetop winds light from the southeast.FRIDAY: A mix of sun and cloud. Freezing levels 2900 m and alpine temperatures near +8 degrees. Ridgetop winds light from the southeast.SATURDAY: Cloudy with light precipitation falling as rain at treeline and below and snow in the alpine. Freezing levels 1800 m and alpine temperatures falling to +1 degree. Ridgetop winds light from the South.
Avalanche Summary
On Tuesday, a widespread natural loose wet and wet slab avalanche cycle occurred up to size 2.5. These avalanches were from sunny aspects (SE-SW) 1700-2000 m. Explosive controlled wet slab avalanches up to size 3 were also triggered on sunny aspects between 1900-2200 m. Continued warming and a lack of overnight re-freeze we expect to see natural avalanche activity to continue.
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
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.
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.