Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain
Weather Forecast
Wednesday: Cloud, with possible light precipitation. Freezing level around 2200 m, dropping to around 1700 m. Moderate southerly winds.Thursday: Light precipitation. Freezing level around 1200 m. Light southerly winds.Friday: Any remaining precipitation clearing by afternoon. Freezing level around 1200 m. Light variable winds.
Avalanche Summary
Recent reports include cornice fall and loose wet avalanches. Full-depth size 2-3 glide avalanches have been releasing on rock slabs.
Snowpack Summary
Very large cornices are looming. Glide cracks have opened up, especially on steep rock slabs. The snow surface has gone through a few days of melt-freeze, creating either a crust or loose, cohesionless snow, depending on the temperature. A buried crust/surface hoar layer from late March, down 60-120 cm, is reported to have gained strength in the Duffey Lake area.
Problems
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.