Continually evaluate conditions as you travel through terrain. Avalanche danger is improving, but temperatures remain warm and riders have recently triggered avalanches on a persistent weak layer.
Westerly winds have redistributed available snow into wind slabs in lee features in the alpine and around treeline. Use caution around ridgecrests, especially where you aren't feeling a surface crust.
Last week's 30 to 60 cm of storm snow has formed a persistent slab above weak layers in some areas. This is a concern where there is a poor bond to underlying sun crust layers on south-facing slopes and surface hoar crystals on north-facing slopes. This problem seems most pronounced in the Selkirks around Nelson and around Kootenay Pass. (read more in this blog).
This layer is getting harder for riders to trigger, but it is possible that it could still produce large, surprising avalanches.
Freezing levels are falling overnight, but the surface snow may not solidly refreeze at lower elevations. Paying close attention to how thick and supportive the surface crust is throughout the day will help you avoid any lingering wet loose avalanche problems below treeline.
Also be cautious on and under alpine avalanche terrain when the sun is cooking it.
WEDNESDAY NIGHT: Clouds clearing through the night. Light rain expected, possibly heavier on the far east end of the region. Moderate southwest ridgetop wind trending to northwest by the morning. Freezing level falling to around 1300 m.
THURSDAY: Sunny with scattered clouds in the afternoon. No new snow expected. Ridgetop wind decreasing to light from the northwest. Freezing level rising to around 1700 m.
FRIDAY: Partly cloudy. No new snow expected. Light southwest ridgetop winds. Freezing level around 2100 m.
SATURDAY: Mostly cloudy. No new snow expected. Light south ridgetop wind. Freezing level around 2200 m.
On Tuesday and Wednesday, widespread, loose wet avalanches were reported due to warm temperatures and/or sunshine (size 1-2).
A few natural and human-triggered wind slabs occurred in the alpine and treeline on Monday (size 1-2).
There have been some notable human-triggered avalanches in Kootenay Pass and the Nelson area in the past week. These large slab avalanches (size 2), failed on either a buried sun crust on solar aspects or surface hoar on shaded aspects. This MIN report from an incident on Saturday near Whitewater is an example of this problem.
On Friday, an operator south of Nelson reported a large slab avalanche (size 3), triggered by a helicopter landing initiating a cornice failure. This avalanche stepped down to a deeper weak layer in the upper snowpack, suggesting that these deeper layers are still possible to trigger with large loads.
50 to 70 cm of settling storm snow exists at higher elevations. New snow depths taper significantly with elevation, with moist and crusty surfaces below 2000 m and on south aspects into the alpine.
Last week's storm snow is bonding poorly to underlying layers in some areas. In the Selkirks, especially north of Nelson, it appears that this snow is bonding poorly to the underlying sun crusts on solar aspects and surface hoar on shaded aspects. In the Monashees, reports suggest that this snow has formed a stronger bond to underlying crusts. Several other crust/facet layers exist in the upper 100 cm of the snowpack. Human-triggered avalanches on these layers are unlikely, but large triggers such as a cornice failure, or a smaller avalanche stepping down to these layers is possible.
