Regions
Kootenay Boundary.
Although temperatures have cooled slightly, human triggered loose wet avalanches remain a concern on Monday, especially at mid & lower elevations where the snowpack remains weak, warm and mushy.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain on Tuesday
Weather Forecast
We're moving into a weather pattern more in keeping with seasonal norms. Monday night's storm should offer a nice refresh at upper elevations and temperatures should remain cool(ish), at least through Wednesday morning.SUNDAY NIGHT: Light south/southeast wind, freezing level lowering to around 1500 m, trace to 5 cm of snow possible.MONDAY: Overcast clearing to scattered cloud cover throughout the day day, light southwest wind, freezing level topping out around 2000 m, no significant precipitation expected during the day.MONDAY NIGHT: Freezing level lowering to about 1500 m with 2 to 8 mm of precipitation expected. This will likely start as rain at lower/mid elevations and should produce a trace to 10 cm of snow at upper elevations. TUESDAY: Broken cloud cover, moderate to strong southwest wind, freezing level holding around 1500 m, 3 to 10 cm of snow possible.WEDNESDAY: Clear skies with cloud cover increasing throughout the day, light northeast wind, freezing level rising to about 1900 m, no significant precipitation expected.
Avalanche Summary
No new avalanche activity to report from Saturday. On Friday natural loose wet activity to size 2 was reported throughout the region.
Snowpack Summary
The current snow surface is quite variable. On higher north aspects above 2000 m you may find some dry, faceted snow. Some of this has been redistributed by southwesterly and northerly winds which may have formed isolated old wind slabs. We're looking at a good overnight refreeze on Sunday night, so most surfaces should have a supportive surface crust Monday morning. The two crusts in the upper snowpack are our biggest concern. The first crust is down 20 to 30 cm and loose wet avalanches have recently slid on this interface. The deeper one down 60 to 95 cm has produced easy shears in test profiles. Avalanches on this interface are unlikely, but possible. The snowpack at mid and upper elevations is expected to continue to gain strength as we enter a period of consecutive nights with below freezing temperatures.
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.