Regions
Kootenay Boundary.
Confidence
Fair - Forecast snowfall amounts are uncertain on Thursday
Weather Forecast
Overnight and Thursday: Strong Southerly winds and moderate to locally heavy precipitation 15-20 mm by morning that will be snow at all elevations (30-40 cms). This storm is expected to continue during the day; however snow fall amounts vary between models. This bulletin is based on another 15-20 mm (20-40 cms at higher elevations) of precipitation before the storm moves out of the region to the East. Freezing levels are expected to remain at valley bottoms except a brief period on Thursday where they may rise to just above valley bottoms.Friday: Light flurries are expected in the wake of the storm as residual moisture collides with the cold air moving in from the North. Expect winds to shift to the East-Northeast during the day.Saturday:Continued flurries for the areas near the U.S. border are expected to accumulate another 5-10 cms during the day. Alpine temperatures near -10.0 with light Southeast winds.
Avalanche Summary
Natural soft slab and loose snow avalanches up to size 2.0 were reported to be releasing down 30-50 cms in the storm snow. Large explosive triggers released loose snow avalanches up to size 2.5 in the Kootenay Pass area.
Snowpack Summary
Recent storm snow has been mostly unconsolidated with no reported new shears. The new storm may have more wind, and may quickly transport all of the available snow into new wind slabs. The wind with the new storm may not bond well to the old surface. It will be important to evaluate the bond and test the amount of force required to cause a shear between these two layers. Skiing and riding conditions have been reported to be very good, but this may change overnight depending on how the new storm and wind transported snow interfaces with the recent storm.
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 Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.