Regions
Kootenay Boundary.
New snow with strong winds is expected to form touchy wind slabs. Use conservative terrain selection and avoid wind-loaded features. At lower elevations, rain may cause loose wet problems.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A storm system will bring light precipitation to the region on Saturday. Models are currently forecasting 5-10mm. Freezing levels will start at over 2000m but should fall to around 1500m by the end of the day meaning rain may switch to snow at many elevations. Alpine winds are expected to be strong from the SW. On Sunday, a weak ridge of high pressure should build bringing a mix of sun and cloud. Freezing levels are forecast to reach around 2000m and alpine winds should be light. Another storm system should reach the region on Monday bringing light precipitation.
Avalanche Summary
On Thursday, skiers were triggering wet sluffing and natural dry sluffing was reported on steep north facing features. On Wednesday, natural and skier-triggered sluffing was reported from steep sun-exposed slopes. On Saturday, wind loaded areas are the biggest concern. New wind slabs will likely be touchy. Loose wet avalanches are a problem at lower elevations where it is raining.
Snowpack Summary
Recent snowfall may be sitting on a sun crust on solar aspects. During the heat afternoon of the afternoon, the snow surface has been reported to be moist or wet at all elevations on solar aspects and up to 2000m on north aspects. At many elevations, melt-freeze cycles are occurring with a weak surface crust forming overnight and then breaking down during the afternoon. Up to 35cm of snow from last weekends storm sits over the mid-March rain crust which is up to 15cm thick. Reports suggest that this snow is bonding well to the crust. Older deeply buried persistent weak layers still exist in the snowpack but are no longer expected to be reactive.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.