Wind slabs in lee features below ridgetops may still be reactive to human triggers on Sunday.
Weather Forecast
SUNDAY: Sunny / Light southwesterly ridgetop winds / Freezing level rising to around 2300 m.MONDAY: Sunny / Light southwesterly ridgetop winds / Freezing level rising to around 2400 m.TUESDAY: Sunny / Moderate to strong southwesterly ridgetop winds / Freezing level rising to around 3000 m.
Avalanche Summary
A widespread natural avalanche cycle occurred near Fernie on Friday. Numerous storm slabs up to size 2.5 were reported primarily on north and northeasterly aspects between 1800-2100 m. These storm slabs will become less of a concern in the coming days but the forecast warming and sunshine may wake up a deeper weak layer on steep south facing slopes resulting in large and destructive avalanches.
Snowpack Summary
20-30 cm of recent storm snow is settling rapidly. This 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 throughout the weekend or by a large trigger such as a falling cornice.
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.