The current snowpack structure is atypical for this region, especially at this time of year. Check out this blog post for more details: http://www.avalanche.ca/blogs/VQxmdCUAAJZDmnXn/rainsnowwind
Confidence
Fair - Due to the number of field observations
Weather Forecast
A ridge of high pressure will form on Sunday delivering a mix of sun and cloud. By Sunday afternoon, an unstable air mass will bring intermittent convective snowfall which should result in light to locally moderate accumulations for the rest of the forecast period. Ridgetop winds should remain generally moderate from the southwest with daytime freezing levels hovering around 1500m.
Avalanche Summary
Over the past week, isolated slab avalanches to size 2 have occurred on persistent weaknesses buried on March 11th. In a few cases, avalanches failed with light inputs such as remote triggers from distances of up to 100m away. New snow and wind has created its own mix of reactive surface instabilities, but it has also added load to these deeper, more destructive layers. There's a fair bit of uncertainty as to how the March 11th interface will react to storm loading. That said, I'd resist heading into aggressive higher elevation as any avalanches on this layer would likely be destructive in nature.
Snowpack Summary
New storm slabs have formed in response to steady wind, snowfall and warm temperatures prior to the weekend. At lower elevations, rain has saturated the snowpack. Cornices may also be fragile. A touchy crust/facet persistent weak layer, buried up to 70 cm down, has started to play up in isolated terrain, especially in the north of the region (see avalanche summary). Avalanche problems associated with this layer may linger for a while with the potential for surprisingly large and destructive avalanches. Below this, the snowpack is reported to be generally well-settled and strong.
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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.