Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Synopsis: Generally very fine weather with cool overnight temperatures and warm, sunny days.Saturday: Cloud lingering, but also some clear breaks. Freezing level 1700 m. Light northerly winds.Sunday and Monday: Clear and sunny. Freezing level around 1600 m. Light southwesterly winds.
Avalanche Summary
A couple of large natural avalanches were reported from northeast of Sparwood that likely ran on Wednesday or Thursday on the buried rain crust. On Friday, a few cornice releases were observed and sluffing was noted in the new snow on steep terrain.
Snowpack Summary
Approximately 40-70 cm recent storm snow sits on top of a buried rain crust that exists up to around 2100 m. In areas near Sparwood, the new snow bonded poorly to this crust, and a few large avalanches were observed that likely released on this layer. In the North Elk Valley, the bond at the crust was reported to be good. Generally, this interface has now become stronger, and is unlikely to release due to the weight of a person alone. However, a large trigger, such as a cornice fall, or an airborne sledder, could potentially trigger a large avalanche on this layer in steep terrain. Recent wind slabs exist in the immediate lee of ridge lines and terrain features. Cornices are large and fragile. Mid and lower snowpack layers are generally well-settled.
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
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.