Confidence
Fair - Timing or intensity of solar radiation is uncertain on Saturday
Weather Forecast
A trough exits to the east Saturday as high pressure builds into the region in the afternoon. Clouds persist through most of the day, but the occasional sunny break is expected. Freezing level rises to 1800 m in the afternoon. Sunday: Sunny skies allow freezing levels to climb to 2000 m. Winds calm, increasing to light out of the E in the afternoon. Monday: Freezing levels spike to 2500 under sunny skies. Treeline winds remain calm/light, ridge top winds moderate SW.
Avalanche Summary
No recent avalanche observations from the region. Control work in the Fernie area Thursday produced avalanches to size 2 with most activity being limited to the 20 cm of storm snow. The storm snow was reportedly quite sensitive to ski cutting, numerous size 1.5 avalanches were triggered in this fashion on N, NE & E facing slopes. A few deeper avalanches were triggered by control work under headwall features too.
Snowpack Summary
The region picked up 20 cm from Wednesdays storm which came to rest on the April 4th melt/freeze crust. An exiting upper trough likely shielded the region from much solar input Friday. Recent storm snow has added up to 60-120 cm depending on the drainage. The storm snow has been failing on a crust on southerly aspects that may have small facets or surface hoar at the interface. High freezing levels and solar radiation have caused wet loose snow avalanches. Large cornices loom over many lee slopes.
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.
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.
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.