Regions
Kootenay Boundary.
Spring Conditions. Sunny skies and very high freezing levels will increase the avalanche danger this weekend. The surface crust may break down rapidly if there is no re-freeze overnight.
Weather Forecast
Cloud overnight decreasing as moderate southerly winds develop as the ridge of high pressure builds. Clearing during the day on Saturday with light southerly winds and freezing levels at 2500 metres. Clear on Sunday with freezing levels rising up to at least 3000 metres and treeline temperatures around plus 10 degrees. Monday should be the warmest day with freezing levels at 3500 metres.
Avalanche Summary
No new avalanches reported. One report of a natural cornice fall size 2.0 on a northeast aspect at 2200 metres on Tuesday.
Snowpack Summary
The snow surface is currently going through a typical spring melt-freeze cycle on all aspects and at all elevations, except possibly high true-north slopes which could be holding onto cold snow. The strength (thickness) of the surface crust and how quickly it breaks down during the day are important factors to focus on. Forecast very warm weather with high freezing levels and strong solar radiation is expected to start to effect high alpine north aspects over the next few days. In some areas this may be the first real heat that the snowpack in these areas has received. Watch for clues that the snowpack is warming up, and stay off big slopes in the afternoon.
Problems
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.
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.
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.