Regions
Kootenay Boundary.
Lingering storm instabilities remain a concern, especially in the alpine. Avoid steep, wind loaded features and large, unsupported slopes. Use extra caution on sun-exposed slopes during the heat of the afternoon.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Light precipitation (2-4mm) can be expected for much of the region Tuesday overnight and Wednesday morning. By Wednesday afternoon the clouds should break and sunny periods are possible. Freezing levels should reach around 2000m Wednesday afternoon and alpine winds should be moderate from the NW. On Thursday, a warm storm system reaches the south coast. There is currently quite a bit of uncertainty regarding the timing and track of the system into the interior regions. For the KB region, it is currently looking like unsettled conditions for Thursday with mainly cloudy conditions and light scattered precipitation. Freezing levels should again reach around 2000m and alpine winds may be moderate or strong from the SW. On Friday, light precipitation is expected but amounts are uncertain. Freezing levels may climb to over 2500m.
Avalanche Summary
On Monday, a natural size 2 avalanche was reported from a steep wind-loaded slope, ski cuts produced several size 1 soft storm slabs, and a skier triggered a size 1.5 storm slab. Lots of natural loose wet avalanches up to size 2 were reported from all aspects in the afternoon. On Wednesday, loose wet avalanches are possible during the heat of the afternoon, especially on sun-exposed slopes. Human-triggering of storm slabs remains a major concern, especially in the alpine. Wind-loaded features and steep, unsupported slopes are the most likely areas to trigger an avalanche.
Snowpack Summary
Heavy rain on Saturday soaked the snowpack up to ridge tops. On Sunday, heavy snowfall (up to 35cm) and southwest winds developed new storm slabs that are still reactive to human-triggering. The new snow sits on the mid-March rain crust that formed during the rain event on Saturday. The mid-Feb layer was down around 20cm before the rain event and there is currently uncertainty as to the status of this layer. Older deeply buried persistent weak layers still exist in the snowpack. These layers have not been reactive lately but the extremes of warm weather followed by heavy loading from rain and snow make it difficult to assess how the snowpack will respond.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
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.