Winter is loosening its grip and a warming event is on its way. Surface instabilities should be the main concern on Saturday. Check out the Forecasters' Blog for more details: http://www.avalanche.ca/blogs/2018-03-09-first-big-warm-up
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
Saturday: A mix of sun and cloud, becoming increasingly sunny. Light south winds, becoming strong in the alpine. Freezing level rising to 1500 metres with alpine temperatures around -3.Sunday: Mainly sunny. Light south winds. Freezing level rising to 1800 metres with alpine temperatures of -1.Monday: Sunny. Light southeast winds. Freezing level rising to 2100 metres with alpine temperatures around 0 to +1.
Avalanche Summary
Thursday's reports included one observation of an older size 2.5 natural wind slab release in the south of the region. This avalanche occurred on a 40 degree southwest slope in the alpine and had a depth of 60 cm.On Wednesday, a chunk of falling ice triggered a size 2.5 avalanche. On Tuesday, a few large cornice falls were reported, without releasing large avalanches on slopes below. A few loose wet solar-triggered avalanches were also observed.Avalanche activity is expected to increase as we move into a period of intense sun and prolonged warming. Predictable loose wet avalanches from steep, sunny terrain should be easy to manage. A trickier problem will gradually emerge as warmth penetrates into the snowpack to tickle deeper persistent weak layers that have lately been dormant in the Cariboos. The next few days will be a time to avoid exposure to large sunny features and keep well away from corniced slopes.
Snowpack Summary
Thursday's storm brought 20-30 cm of new snow by Friday morning. This new snow overlies well-settled storm snow from regular snowfalls over the past couple of weeks. Although several layers of sun crust can be found within this storm snow on solar aspects, recent snowpack tests have not been producing concerning results in the upper snowpack. Persistent weak layers from early January and mid-December are still being reported by local operators. They are generally considered dormant, but could wake up with forecast warming, a surface avalanche stepping down, a cornice fall, or a human trigger in a shallow or variable-depth snowpack area. These layers consist of sun crust, surface hoar and/or facets. A weak layer of facets also lingers at the base of the snowpack.
Problems
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.
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.