Purcells

Forecast light new snow amounts shouldn't be enough to form new wind slabs in most areas, so sunshine is expected to once again drive loose wet avalanche problems on Tuesday.

Moderate - Forecast snowfall amounts are uncertain

Monday night: Mainly cloudy with isolated flurries and a trace of new snow. Light south winds, increasing to strong southwest in the alpine.Tuesday: Mainly cloudy with scattered flurries bringing 2-7 cm of new snow, decreasing overnight. Moderate to strong southwest winds. Alpine high temperatures around -3 with freezing levels to 1700 metres.Wednesday: A mix of sun and cloud. Light east winds. Alpine high temperatures around -3 with freezing levels to 1900 metres.Thursday: Sunny with cloudy periods. Light northeast winds. Alpine high temperatures around -1 with freezing levels to 2000 metres.

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.Looking forward, avalanche danger will remain linked with daytime warming and especially sun exposure. Light new snow amounts forecast for Tuesday will be the first to shed from steeper slopes as warming takes effect.

Trace amounts of new snow have begun to accumulate above a surface of melt-freeze crust in most areas above 1500 metres, with the exception of limited north aspects above 2000 metres, where it may land on settled dry snow. Below about 1500 metres, it will land on variably isothermal (slushy) and crusty surfaces. 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.