Strong winds will continue building fresh wind slabs while an alpine freezing level may promote instability at higher elevations on Sunday
Confidence
Moderate - Freezing levels are uncertain on Sunday
Weather Forecast
Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Winds strong from the southwest. Freezing level to 1000 metres with alpine temperatures of -5. Possible alpine temperature inversion bringing alpine temperatures to above zero.Monday: Mainly cloudy with isolated flurries and a trace of new snow. Winds moderate to strong from the west. Freezing level returning to valley bottom with alpine temperatures of -6.Tuesday: Mainly cloudy with flurries bringing a trace to 5cm of new snow. Winds light from the east. Alpine temperatures around -10.
Avalanche Summary
No new natural avalanches have been reported, but small pockets of wind slab were found reactive to ski cutting on Saturday. A similar report from Friday details a Size 1 wind slab avalanche triggered by a skier on a northeast facing slope in the north of the region. Our ongoing strong winds can be expected to continue forming thin, reactive slabs while loose snow remains available for transport.
Snowpack Summary
A dusting of light snow covers settled storm snow from last week. Last week's storm delivered 20-40 cm of heavy snow with freezing levels up to 1600 m. Crusts can be found near the surface on solar aspects at high elevations and on all aspects below 1600 m. The lower snowpack appears to be well settled. There have been isolated reports of surface hoar layers that formed in early January that may still exist about 40 cm deep in sheltered areas. In the First Peak area on Wednesday, the height of snow was 140 cm at an elevation of 1950 metres. The top 50 cm of the snowpack was pencil resistance hard above a softer layer of December facets, and the November crust in this location was 15 cm thick and breaking down into weak faceted crystals.
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.