As winter returns, wind and new snow will build pockets of wind slabs in lee areas in the alpine as well as exposed treeline areas. Assess how the new snow is bonding to the old crust before jumping in to any committing terrain.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Tuesday: Flurries, accumulation 5 cm. Moderate to strong southwest wind. Alpine temperature near -5. Freezing level 1100m.Wednesday: Mix of sun and cloud, isolated flurries. Moderate to strong west wind. Alpine temperature near -5. Freezing level 1000m.Thursday: Cloudy, isolated flurries. Strong west wind. Alpine temperature near -5. Freezing level 1000m.
Avalanche Summary
Large loose, wet avalanches were reported during last week's rain event. With the arrival of cooler temperatures over the weekend reports indicate that the snow surface has refrozen and no new avalanche activity has been reported. As wind redistributes the new snow however expect to find wind slabs in lee areas.
Snowpack Summary
At upper elevations about 5-10 cm of snow has fallen on the crust that formed after last week's rain and warm weather. The crust is up to 10 cm thick and extends to mountain top elevations on all aspects. The snowpack below the crust is moist to ground. Rain has washed away much of the snow below treeline.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.