Forecast wind and new snow will increase the avalanche danger. New storm slabs are expected to be widespread in the alpine and at treeline.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Snow and moderate southerly winds overnight with freezing level down to 500 metres. Expect 15-25 cm in the alpine by Friday morning. Snow continuing during the day with strong westerly winds, expect another 10-15 cm during the day. Light snow overnight and during the day Saturday. Heavy snowfall Sunday morning and during the day Sunday combined with strong southwest winds.
Avalanche Summary
No new natural avalanches reported.
Snowpack Summary
The new storm is expected to develop widespread storm slabs above the old surface of loose snow at treeline and wind affected snow in the alpine. Northerly winds transported some snow on Wednesday into soft wind slabs on lee aspects. There were some reports of easy test results between the wind slab and the old storm snow below. These new wind slabs overlie 40-50cm of storm snow from last weekend. Limited observations suggest the recent storm snow has gained considerable strength, although I'd continue to be wary of lingering pockets of wind slab on high elevation, wind-loaded slopes. On steep, south-facing terrain you may find a sun crust from solar warming on Monday. Below 2200m, a hard rain crust can be found approximately 120cm below the surface.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.