Regions
South Coast Inland.
Human triggered slab avalanches may become more likely as warm temperatures allow the storm snow to settle into a more cohesive slab. Keep a close eye on steep sun exposed slopes throughout the day too, warming may initiate natural loose avalanches.
Weather Forecast
A warm dry pattern is expected for the next few days. The upper ridge will shift eastward on New Year's Day, which opens the door to warm air drifting in from the eastern pacific. This pattern is expected to stick with us for the foreseeable future. MONDAY: Temperature Inversion with below freezing air in the valley, above freezing (warmer) air between 1700 m and about 2500 m. Scattered cloud, light variable wind, no snow expected.TUESDAY: Temperature Inversion with below freezing air in the valley, above freezing (warmer) air between 1500 m and about 2800 m. Scattered cloud, light southwest wind, no snow expected.WEDNESAY: Temperature Inversion with below freezing air in the valley, above freezing (warmer) air between 1500 m and about 2800 m. Clear skies at dawn, a few clouds in the afternoon, light southwest wind, no snow expected.
Avalanche Summary
On Saturday a widespread avalanche cycle to size 1.5 was reported with avalanches failing within the recent storm snow. A natural avalanche cycle likely occurred Friday night during the storm and may have continued into early Saturday morning.
Snowpack Summary
Friday night's storm produced about 30 cm in the north of the region and almost 40 cm in the south. That brings the total from the two successive storms to approximately 50 to 80 cm. The bulk of the wind during the storms was out of the southwest, south and southeast but there were periods of northeast and easterly winds too. All of this new snow rests on a variety of old surfaces including crust on solar aspects, old wind slabs, facets and isolated surface hoar below treeline. Wind slabs are common in wind exposed terrain, but it's thought the snow is largely unconsolidated in protected areas. As temperatures begin to warm on Monday the storm snow will likely settle into a more cohesive slab. A widespread melt-freeze crust buried mid-December exits throughout the region. This crust is down around 30 to 60 cm in the Duffey. Around the Coquihalla it's about 100 cm below the surface. This layer has not produced much in the way of avalanche activity, but it could come to life as the overlying slab gains cohesion.Beneath the mid-December crust, the lower snowpack is generally strong and well settled.
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.