Cloudy areas should see loose wet avalanche problems diminish a bit on Monday. Expect more of the same active loose wet avalanche conditions on any slopes that see strong sun.
Weather Forecast
Sunday night: Mainly cloudy. Light south winds.Monday: Mainly cloudy with isolated flurries bringing a trace of new snow. Light rain below about 1600 metres. Light south winds. Alpine high temperatures around 0 with freezing levels to 2000 metres.Tuesday: Cloudy with scattered flurries bringing a trace to 10 cm of new snow. Light rain below about 1200 metres. Precipitation easing overnight. Light to moderate southwest winds. Alpine high temperatures around -3 with freezing levels to 1600 metres.Wednesday: Mainly cloudy. 24 hour new snow totals of approximately 5-20 cm. Light east winds. Alpine high temperatures around -3 with freezing levels around 1700 metres.
Avalanche Summary
Many wet loose avalanches were observed between last Sunday and Friday. They were large (up to size 3), occurred mostly on southeast to southwest aspects, and at all elevations. Many of these avalanches scoured to basal weaknesses. A notable deep persistent slab avalanche released on Wednesday, likely triggered by a cornice fall. It was 100 cm deep on a northeast aspect at 2900 m.
Snowpack Summary
Forecast trace snowfall will accumulate above a surface of melt-freeze crust in most areas above 1500 metres, with the exception of north aspects above 2000 metres, where it will land on settled and preserved dry snow. Below about 1500 metres, light precipitation as rain will land on variably isothermal (slushy) and crusty surfaces. Any added moisture will promote isothermal conditions where they don't already exist. The mid snowpack is generally consolidated and strong, but exceptions may exist on north aspects above 2000 m, where a gradually strengthening layer of faceted grains buried 40 to 60 cm deep may still be preserved below an overlying slab of old and hard wind-affected snow.The base of the snowpack is composed of weak faceted snow which may coexist with a melt-freeze crust. One very large persistent slab was observed to have failed at this layer during the recent warming event.
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.