Natural avalanche activity continued today in specific terrain. There are numerous buried layers of concern. Take the time to evaluate these before making terrain decisions.
Weather Forecast
Wednesday will be cloudy with light flurries and accumulations between 5 and 10cm. Temperatures will reach -5 °C. Winds will be strong from the southwest. Not much snow is expected from the occasional flurries on Thursday and Friday.
Avalanche Summary
Several slab avalanches have occurred in the past 24 hours up to size 2.5. These slides occurred in steep Alpine terrain on north, east and south aspects. Fracture depths range from 40 to 80cm, corresponding with the Dec 15th interface in most cases. Yesterday a size 3.0 naturally triggered slab avalanche occurred on a steep north aspect in the Alpine and ran full path.
Snowpack Summary
A few cm's of new snow fell last night. With a week of very strong winds wind slabs are widespread in alpine and treeline terrain and have snuck themselves into open areas below treeline. Expect to find hard slabs in the alpine and a mix of hard and soft slabs everywhere else, except where the winds have stripped the snow down to bare rock. Cornices have grown significantly in the past few days and are now very large and looming. At 2250m and below there are 3 layers of buried surface hoar. These are referred to as the Jan 18th, Jan 6th and Dec 15th surface hoar layers, down 25, 50 and 100cm respectively. All of these layers appear reactive at the moment. The deeply buried November and October crusts are being tracked and may come alive in shallow snowpack areas.
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.