Sunshine and warming will increase hazard throughout the weekend. Natural loose wet avalanches are expected on steep south facing slopes and lingering storm slabs reactive to human triggers.
Weather Forecast
SATURDAY: Sunny / Light southwesterly ridgetop winds / Freezing level rising to around 1500 m.SUNDAY: Mostly sunny / Light southwesterly ridgetop winds / Freezing level rising to around 2000 m.MONDAY: Sunny / Light southwesterly ridgetop winds / Freezing level rising to around 2300 m.
Avalanche Summary
Several size 2 natural storm slab avalanches and numerous human triggered storm slabs up to size 1.5 on all aspects and elevations were observed near Fernie on Thursday.
Snowpack Summary
20-30 cm of new snow is sitting on a sun crust on solar aspects. Cornices are large and prone to failure over the weekend caused by forecast sunny skies.In the upper to mid snowpack, a surface hoar or facet layer buried mid-February is now 80 to 110 cm below the surface on sheltered northerly aspects. Deeper in the snowpack, the widespread mid-December and late November weak layers are composed of a combination of crusts and sugary facets which are down 200-300 cm. These layers have been dormant but may be awoken by the warm and sunny weather over the weekend or by a large trigger such as a falling cornice.
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.
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.