Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain
Weather Forecast
Thursday: A mix and of cloud, sun and light precipitation. Freezing level around 1600 m. Light southerly winds.Friday: Light precipitation, dissipating. Light winds. Freezing level around 1500 m. Saturday: Clearing skies. Light south-westerly winds. Freezing level rising to around 2000 m.
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 melt-freeze crust exists on solar aspects and at low elevations. In some areas, limited overnight cooling has kept surface snow from re-freezing, leaving it loose and cohesionless. Areas of wind slab formed with recent southerly or easterly winds. Pockets of snow can be found on high north aspects, now buried underneath wind slabs in some areas. A predominately crusty weak interface from late March, now down 50-190 cm, has become less likely to trigger, but remains a lingering concern.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
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.