Spring "power flurries" may produce more snowfall than forecast. Pay close attention to how much snow falls in your area and select terrain accordingly.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Sunday
Weather Forecast
On Sunday night and Monday morning expect 10-25cm of new snow and moderate southwest ridgetop winds. On Tuesday and Wednesday the region should see a mix of sun and cloud with generally light northwest winds. The freezing level should hover around 1400m for the forecast period. Note: Due to the convective nature of the Sunday night's weather pattern, the track and intensity of the precipitation is tough to pin down. There could be localized areas where snowfall total exceed 30cm.
Avalanche Summary
On Saturday quite a few size 1-2 storm slabs were observed failing naturally or by ski cutting. They formed in response to new snow and wind and were mostly triggered on north to northeast facing terrain at treeline and in the alpine. No new persistent slab avalanches were observed in the South Columbia region on Saturday; however, a few were noted in the size 2-3 range in the neighboring North Columbia and Kootenay Boundary regions sliding on the late February layer. They failed either naturally or under light loads on various aspects at treeline and in the alpine. This intermittent pattern is spooky, and sporadic persistent slab avalanches can be expected in the South Columbia region as well. With more snow and wind on the way, watch for new wind slab activity throughout the region on Monday.
Snowpack Summary
On Saturday and Saturday night highly variable amounts of new snow fell (10-47cm) throughout the region. Moderate ridgetop winds that developed at the tail end of the storm likely formed soft slabs in leeward terrain at treeline and in the alpine. 60-110cm below the surface you'll find a persistent weak layer comprised of surface hoar, facets and/or a thick crust. This layer, which was buried on February 27th, seems variably reactive. In other words, it's still touchy in some places while in other places it's really tough to trigger, and there's not much of a reliable pattern telling us what exact aspects are most suspect. I'd continue to be suspicious of steep, unsupported features at treeline and in the alpine as this layer has the potential for very large avalanches. Below this interface, the snowpack is generally gaining strength. At ridgetop, cornices are huge and potentially unstable.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.