Snow accumulating this past weekend has likely formed new slabs and increased the load on a buried weak layer. The effects may be greater in the east of the region where snowfall amounts have been higher.
Around 30 to 60 cm of snow overlies a weak layer of surface hoar. The layer has been most problematic on northwest to northeast aspects between 1600 m and 2300 m, but the layer may exist on all aspects and at all elevations. Assess the layer prior to committing to avalanche terrain or adopt a conservative mindset to avoid the problem.
Around 15 to 30 cm of snow fell in the region, with the most in the east (e.g., Kootenay Pass). As this snow consolidates, it will form storm slabs. Use added caution on sun-exposed slopes when the sun is shining, as it could rapidly deteriorate the storm snow and trigger loose dry or slab avalanches.
SUNDAY Night: Cloudy with clear periods, moderate southwest wind, alpine temperature -9 C, freezing level 1000 m.
MONDAY: Clear skies, light west wind, alpine temperature -7 C, freezing level 1100 m.
TUESDAY: Mix of sun and cloud, light southwest wind, alpine temperature -6 C, freezing level 1200 m.
WEDNESDAY: Mix of sun and cloud, light west wind, alpine temperature -4 C, freezing level 1400 m.
Saturday's reports indicate several explosives controlled storm slab avalanches size 1 to 2 on all aspects between 1900 and 2100 m.
On Friday, a few small (size 1.5) avalanches released on the surface hoar layer described in the Snowpack Summary. They occurred on northerly aspects around 2000 m and were 20 to 30 cm deep. Over the past two weeks, small to large (size 1 to 2) avalanches have released on the surface hoar layer. They have most often released between 1800 and 2300 m on northwest to east aspects. This trend is suspected to continue as this layer slowly gains strength.
Around 10-15 cm of snow fell in the west of the region and 20 to 35 cm in the east of the region over the weekend. Storm slabs are likely developing as the snow consolidates. The wind remained light to moderate from the southwest, so wind slab formation may be limited to immediate lee features.
The snowfall is loading a touchy layer of feathery surface hoar crystals that is found 30 to 60 cm deep. The layer is most commonly found in open trees (e.g. in this MIN) or sheltered terrain around upper below treeline, treeline, and lower alpine elevations. Check out the latest forecaster blog that offers a deeper dive into these conditions.
The remainder of the snowpack is strong and well-settled.
