Watch for hidden pockets of wind slab on Monday after getting buried by a bit of new snow Sunday evening.
Weather Forecast
Mainly cloudy today with alpine high around -6 deg. A weak low pressure system should bring up to 5cm of snow tonight. By Monday afternoon an arctic front will make it's way south bringing more sunshine, cool temperatures and light northerly wind with freezing levels staying close to valley bottom. More light snowfall is expected on Thursday.
Snowpack Summary
Surface conditions include surface hoar, faceting snow, sun crust on South aspects, wind crust, and pockets of soft snow and slab in isolated locations and hard crust bellow 2000m. Feb 18 surface hoar down 20cm, variable distribution to 2200m. Feb 14 crust down 20-25, up to 10cm thick. Persistent weak layers down 1-1.5m are stubborn to trigger.
Avalanche Summary
No new avalanches were observed yesterday. Recent natural avalanche activity has been limited to small skier triggered avalanches on isolated wind slabs and sun triggered loose avalanches on steep solar aspects.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.