Purcells

Overnight snow and moderate winds shifting northwest will continue to form wind slabs and elevate avalanche hazard at upper elevations. Crusty surfaces below treeline will make for low hazard but difficult travel conditions.

Convective instability behind the storm will bring additional snowfall to some areas overnight Sunday and into Monday. Specific locations and amounts are notoriously difficult to forecast for this type of weather pattern.

Sunday night: 5-10 cm new snow. Moderate to strong northwest wind. Freezing level valley bottom. Alpine temperatures around -12.

Monday: Mix of sun and cloud with isolated flurries. Moderate northwest wind. Freezing level 500 to 1000 m. Alpine temperatures around-12.

Tuesday: Mix of sun and cloud. Light westerly wind. Freezing level 1500 m. Alpine temperature -7.

Wednesday: Sunny. Light southwest wind. Freezing level 2100 m. Alpine temperature -1.

We are awaiting reports of avalanche activity from the weekend's storm. Prior to the storm, recent avalanche activity has been limited to small (size 1-1.5) wind slab avalanches, dry loose sluffs, and cornice falls.

10-20 cm of new snow has likely been redistributed by wind at upper elevations. Crusty surfaces exist below treeline. A widespread crust layer from the mid-March warm spell can be found 30-60 cm deep, and small surface hoar has been observed at this depth on some isolated north-facing slopes. Reports suggest the snow is generally well bonded to these layers. Deeper layers are strong and have been unreactive over the past few weeks.

• Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
• Recent wind has varied in direction so watch for wind slabs on all aspects.
• Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.