Isolated Wind slabs exist up high and soft slabs at lower elevations is the story today. The next storm moving in on Friday has the potential to overload the January 17th surface hoar, resulting in a widespread cycle.
Weather Forecast
Mainly sunny today, the alpine may reach -7 on solar aspects, winds will be light from the NW, and no precipitation. Some clouds will move in tonight, flurries starting tomorrow accompanied by rising freezing levels and SW winds. A low pressure system will move over us later this week, we may see 30-40cm of new snow by Saturday.
Snowpack Summary
Extreme winds over the weekend created wind slabs on specific terrain features in the alpine and treeline. Soft slabs exist at treeline and below as the January 17th surface hoar is being incrementally buried. This layer is now buried 25-45cm, it is most reactive between 1400-1900m, and where it overlies a crust on steep solar aspects.
Avalanche Summary
Extreme winds over the weekend triggered a natural cycle in the HWY corridor to size 3, these avalanches were mainly out of extreme terrain. Reports from the back country included skier accidentals and naturals ranging in size from 1.5 to 2 at and below treeline, failing on the January 17th surface hoar.
Confidence
Due to the number and quality of field observations
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.