Spring Conditions. Sunny skies and very high freezing levels will increase the avalanche danger. The surface crust holds the snowpack together and may break down rapidly if there is no re-freeze overnight.
Weather Forecast
Overnight freezing level at 3500 metres under clear skies with light southwest winds. Clear and sunny on Tuesday with light southwest winds and freezing levels at 3500 metres. Clear and sunny on Wednesday with light winds and freezing level at 3500 metres. Some uncertainty regarding when the ridge of high pressure will break down; at this time about 50-50 chance of sun or cloud on Thursday. Freezing levels will start to drop after the ridge breaks down and moves eastward.
Avalanche Summary
No new avalanches reported, but we have very few eyes and ears still in the mountains reporting. Most commercial operations in the region have finished their season and data is sparse.
Snowpack Summary
Cornices are large, fragile, and could trigger deep slab avalanches that run to valley bottoms. Monitoring the overnight freeze of the snow surface is very important.. If the snow surface does not freeze overnight or if the crust is only a few cm thick, the effect of daytime heating and solar radiation will weaken the snowpack much quicker. There is an old crust layer down approximately 50cm in the Duffey area and north of Pemberton. Though mostly dormant, it produced a couple large avalanches during the last major warming event. The forecast hottest weather of the year to date could again test it, especially in isolated locations such as steep, rocky faces. Glide cracks are widespread, active, and best avoided. Low elevation and thin snowpack areas have become isothermal, meaning the snowpack is 0 degrees Celsius throughout. An isothermal snowpack is more prone to full depth wet slab avalanches during the heat of the day, especially on steep, smooth slopes.
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.