Regions
Kootenay Boundary.
Cornices and solar aspects are important to watch right now. Pay close attention to rising temperatures.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Thursday
Weather Forecast
A series of Pacific frontal systems will pass through the area in the next 4 days bringing cloudy skies and small amounts of precipitation. TONIGHT: Snow flurries above 1800m, light rain below. 12 TUESDAY: Cloudy with flurries and/or light rain, no significant precipitation. The freezing level will drop to 1200 m overnight, then climb to 1800m during the day, winds will be light, south to south west. WEDNESDAY: Light precipitation in the late afternoon, winds forecast to be light from the south, freezing level dipping overnight to 1000 m, then climbing to 1600 m during the day. THURSDAY: 10mm of precipitation in the forecast with the freezing level at 1400m early in the day and rising to 1600 in the afternoon. 10 to 15 cm of snow accumulation possible above1200m, winds are forecast to belight from the west.
Avalanche Summary
There are several reports from yesterday of loose-wet and moist point release avalanches, some natural and some skier triggered. Snowballing and pinwheeling have also been mentioned in the region on steep southerly aspects. No reports of cornice failures from yesterday, but they are still on everyone's mind!
Snowpack Summary
Warm temperatures and strong solar radiation have encouraged bonding of the last blast of storm snow. Be aware that there are still multiple buried crusts at treeline and below, but they have not been reactive recently. The late February (Feb 27th) persistent weak layer of buried surface hoar, is now down 70 to 120 cm. This layer has been the interface for some large avalanches and is worth keeping in mind ( and perhaps looking for by digging a test pit) We suspect that this weak layer is more prominent on northerly (shaded) aspects at and above 1700 m. It may also be found associated with a crust on solar aspects. There have not been avalanches on this layer recently, but it is still a concern in the region. The potential is there for deep weak layers to become reactive. Cornices and exposure to cornice run-outs are definitely still something to be concerned about. Light to moderate south winds accompanying the incoming precipitation may build wind slabs on lee ( N-NW ) features in the coming days. As the sky clouds over and the freezing level lowers, it's worth paying attention to moist or wet surface snow.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.