Confidence
Fair - Freezing levels are uncertain for the entire period
Weather Forecast
Friday: Clouds and a few cm of snow, falling as rain below about 1400 m. Freezing level around 1600 m. Light northerly winds.Saturday: cloudy with sunny breaks. Light, variable winds. Freezing level around 1500 m.Sunday: Warm, dry and cloudy. Freezing level rising to 1800-2000 m. Light winds, increasing from the SW by evening as a low pressure system approaches.
Avalanche Summary
On Tuesday, several size 1-2 loose moist avalanches were triggered by solar warming or by people. On Sunday, a natural and human-triggered wind slab cycle occurred on north-west and west aspects following overnight winds. A size 3 natural slab is suspected to have stepped down to the March crust on Monday. It failed on a sun-exposed south-west aspect at 2300 m. There has also been some cornice fall.
Snowpack Summary
A generally strong and deep spring snowpack exists. A crust layer from late March, buried within the upper 2 m of the snowpack, remains a concern. Recent warm weather has led to moist snow on all aspects to about 2200 m, which is expected to have formed a crust, now covered by a small amount of new snow. On north aspects above about 2400 m, dry snow may still be found. Large cornices threaten slopes and glide slab releases are a possibility, especially in steep rocky terrain.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.