Avalanche problems that peaked during the warm spell should diminish on Monday, but not disappear.
Weather Forecast
Sunday night: Cloudy with isolated flurries bringing a trace to 5 cm of new snow, with light rain below about 1100 metres. Light to moderate south winds.Monday: Mainly cloudy with isolated flurries bringing a trace of new snow. Light rain below about 1500 metres. Precipitation continuing overnight. Light to moderate south winds. Alpine high temperatures around 0 with freezing levels to 1900 metres.Tuesday: Cloudy with continuing flurries bringing 5-10 cm of new snow, with new snow totals to 10-15 cm. Precipitation easing overnight. Moderate southwest winds. Alpine high temperatures around -3 with freezing levels around 1600 metres.Wednesday: A mix of sun and cloud. Light northeast winds. Alpine high temperatures around -1 with freezing levels to 1800 metres.
Avalanche Summary
The wet loose avalanche cycle from last Sunday to Friday diminished as cooler, seasonal temperatures returned to the mountains on Saturday. Evidence of the cycle is widespread at all elevations, with recent avalanches up to size 3 found mostly on southeast to southwest aspects. Numerous persistent and wet slab avalanches were also triggered naturally, by skiers, and explosives on Thursday and Friday. They occurred on all aspects and generally at treeline and alpine elevations. They were most often 30 to 50 cm deep.Looking forward, avalanche problems will be split between lingering loose wet problems (areas of isothermal snow that haven't already avalanched) and isolated persistent slab problems on high north aspects. The latter may present as a large old wind slab that remains triggerable because it sits on an interface of preserved cold, faceted (sugary) snow. Small new wind slabs are expected to form gradually as new snow accumulates at higher elevations.
Snowpack Summary
Forecast light new snow amounts 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 bury settled and preserved dry snow. Below about 1500 metres, precipitation as rain will land on variably isothermal (slushy) and crusty surfaces. This moisture will promote isothermal conditions where they don't already exist. The remainder of the snowpack is generally consolidated and strong. Exceptions may exist on northerly 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.
Problems
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.
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.