Regions
Kootenay Boundary.
Recent new snow and moderate to strong northwest / southwest winds have created wind slabs at upper elevations. These may be most reactive on shady aspects. Reduce your exposure to sunny slopes if the sun makes an appearance.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Saturday
Weather Forecast
There may be some significant periods of sunny weather on Saturday before a weak system comes through on Sunday. Temperatures are staying cool for this time of year. SATURDAY: A mix of sun and cloud / Light to moderate west wind / Alpine temperature -4 / Freezing level 1500m SUNDAY: A mix of sun and cloud with some flurries (5-10 cm possible) / Light to moderate south west wind / Alpine temperature -5 / Freezing level decreasing to 1300m MONDAY: Mix of sun and cloud and some lingering flurries / Light to moderate northwest wind / Alpine temperature -7 / Freezing level 1000m
Avalanche Summary
On Friday, cornice control work resulted in triggering a size 2 wind slab below, on an east aspect near 2200m. Slab depth averaged 20cm. Tuesday's reports focus on a few natural storm slab avalanches size 1.5-2 on northeast and northwest aspects at 2200m. On Monday there were reports of numerous explosives and naturally triggered storm slab avalanches size 1.5-2 on all aspects in the alpine and tree line.
Snowpack Summary
30-60 cm of recent snow sits on a crust at all elevations on solar aspects and all aspects below 1900 m elevation. Winds were moderate to strong from the north west on Wednesday (switching to southwest by Friday) , creating fresh wind slabs on down wind (lee) aspects at higher elevations. On northerly aspects at and above tree line the storm snow is burying a mix of large surface hoar and surface facets. Two other weak layers are present in the upper snowpack. A layer buried mid March is down 30 to 60cm is crust on solar aspects and surface hoar on high elevation north. A layer buried early March is 50 to 80cm below the surface and is similar in composition to those just described.A few other persistent weak layers are buried in the mid and lower snowpack, but they have gone dormant and are unlikely to resurface until we move into a period with consecutive above-freezing nights.
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.