Regions
Kootenay Boundary.
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
Low - Intensity of incoming weather systems is uncertain on Sunday
Weather Forecast
Forecast amounts of new snow are uncertain on Sunday into Monday. Temperatures are staying cool for this time of year. SUNDAY: Cloudy with some flurries (5-10 cm during the day; another 10cm overnight) / Light to moderate south west wind / Alpine temperature -5 / Freezing level decreasing to 1300m MONDAY: Cloudy with some lingering flurries / Light to moderate northwest wind / Alpine temperature -7 / Freezing level 1000m TUESDAY: A mix of sun and cloud / Light to moderate west wind / Alpine temperature -4 / Freezing level 1500m
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
Warm temperatures and sun over the long weekend resulted in moist surface snow on sunny aspects, and firm crusts when the surface froze overnight. 30-60 cm of snow from last week 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 old storm snow is burying a mix of large surface hoar and surface facets. Another weak layer buried mid March is down 50 to 80cm and is a crust on solar aspects and surface hoar (to 6mm) on high elevation north. The surface hoar is still giving sudden collapse test results.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.