Regions
Kootenay Boundary.
Surface instabilities and cornice hazards should be firmly on your radar as you travel. Expect stability to deteriorate over the course of each day.This is our last regular forecast of the season and will expire on April 25.
Weather Forecast
Tuesday: Sunny. LIght south winds, moderate at ridgetop. Freezing level to 3400 metres. Alpine high temperatures around +8. Weak overnight cooling.Wednesday: Sunny. Light northwest winds. Freezing level rising from about 2700 to 3500 metres by evening. Alpine high temperatures around +9.Thursday: Sunny. Light south winds. Freezing level to 3700 metres with alpine high temperatures around +11.
Avalanche Summary
No new avalanches have been reported although there was likely a round of wind slab activity on Saturday in response to Friday night's snow and wind. The new snow will likely be quick to settle and gain strength in the coming days. With that said, loose wet avalanches and cornice falls are expected with warming and solar radiation forecast for this week. Although less likely, warming may also trigger unexpectedly deep and destructive slab avalanches failing on weaknesses which formed earlier in the season.
Snowpack Summary
A new surface crust is likely to exist on all but north aspects in the high alpine and is expected to undergo melt-freeze cycles with daily warming and overnight cooling. Below the surface, new snow and wind from Friday night and Saturday formed relatively small wind slabs in upper elevation lee terrain. Depending on aspect and elevation, the new snow likely overlies a melt-freeze crust or settled storm snow from earlier in the week.Numerous other melt-freeze crusts exist in the upper snowpack from rain, sun, and warming during the spring season. The mid and lower snowpack are generally well-settled and strong; however, weaknesses deep within the snowpack have the potential to 'wake-up' in isolated terrain with forecast warming and solar radiation, or with a large cornice trigger.
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.