Kootenay Boundary

Heavy snowfall and strong winds have blanketed the region with touchy storm slabs. Conditions on Sunday will be primed for human triggered avalanches.

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An unsettled pattern opens the door to a string of relatively small low-pressure systems that should deliver modest snowfall to the region through the forecast period. Cold air currently in place will help to keep freezing levels low, at least through Tuesday afternoon. All bets are off Wednesday, when the weather models show an influx of moist warm air that will likely push the freezing level up towards 2000m and deliver 10 to 30mm of precipitation.SUNDAY: Overcast skies, freezing level near valley bottom rising to 500m in the afternoon, moderate SW wind, 1 to 5cm of snow.MONDAY: Overcast skies, freezing level around 500m, moderate SW wind, 1 to 5cm of snow.TUESDAY: Overcast skies, freezing level rising to about 700m in the afternoon, potentially pushing to 1500m in the evening, moderate to strong SW wind, 1 to 5mm of precipitation expected.

Reports from Friday include several storm slab and wind slab observations from Size 1-2.5. These avalanches were triggered naturally as well as with ski cutting and explosives. All aspects seemed to share fairly equal representation and crown fractures have generally been limited to the depth of our recent storm snow.On Thursday control work produced storm slab avalanches to size 1.5 on NE, E and SE facing slopes. Reports from Wednesday include numerous natural, skier and explosive triggered storm/wind slab avalanches up to Size 2.Looking forward, we should see a decline in natural avalanche activity while the potential for human triggering at the full depth of our recent storm snow persists for a few more days.

A wide-ranging 35 to 100cm of snow has fallen in the last week. The snowfall was initially accompanied by strong northwest winds, though these have since shifted to the SW. These winds have promoted the formation of touchy storm and wind slabs in lee areas at higher elevations. The new snow has been bonding poorly to a sun crust on previously sun-exposed slopes, as well as faceted surface snow and large surface hoar on shaded aspects. A variety of crusts and thin surface hoar layers in the upper snowpack have been an increasing concern as new snow and wind have loaded the upper snowpack. Areas with a shallow snowpack (less than around 170 cm) generally have a weak snowpack structure with a deep persistent weakness of facets near the ground. There are a number of great MIN reports from Thursday and Friday here: https://avalanche.ca/mountain-information-network/submissions/