A snow storm arrived this afternoon. With it, we are expecting all of the usual, short term avalanche problems: cornices, loose dry and storm slabs are on the radar. Ski quality will be very good in sheltered, low elevation areas.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
Snow. Tonight we are expecting another 5cm followed by another 10 tomorrow. The winds will be strong throughout the storm. Tomorrow ridge top winds will be steady at 30km/hr, but gusting to 60. It will be -9 in the alpine. After tomorrow, we're expecting the snow to be replaced with the usual unsettled spring weather.
Avalanche Summary
No new activity seen today, however visibility was very limited. Loose dry avalanches were almost certainly happening in the alpine.
Snowpack Summary
10-15cm new snow overnight at treeline elevations. This initially came with moderate, gusty winds which faded away during the day today. That has given very soft storm slabs in exposed, immediate lee areas. There was some cracking today in freshly wind loaded areas, however the slabs weren't stiff enough to get going. Looking ahead, the winds aren't done yet, so more slab development is expected. As for the the alpine, storm slabs will be found on all lee (N-E aspects) slopes. They will become more and more active as the storm goes on. Likewise, cornices have grown throughout the day. Below treeline is not too concerning at the moment, but the additional load will add up.
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.
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.