Conditions are generally better in the Monashees than in the Selkirks.
Confidence
Poor - Timing or intensity of solar radiation is uncertain
Weather Forecast
Sunday: Sunny. Freezing level near 2300m. Light winds.Monday/Tuesday: Cloud and light precipitation. Temperatures staying mild. Freezing level near 2000m. Light winds.
Avalanche Summary
Loose solar-triggered avalanches were observed on Friday and a very large (up to 10 m high) cornice collapsed at 2400 m on a NE aspect in the Monashees. On Thursday, a very large avalanche (size 3) ran naturally on a south aspect all the way to valley bottom and part-way up the other side. On Wednesday, a size 3 slab failed on the mid-Feb weakness on a west aspect, with a 2 m deep crown. It was suspected that solar warming was the trigger. While avalanche activity on this layer is no longer widespread, large avalanches continue to occur on a sporadic basis. Last weekend, size 3-3.5 slabs, 100-180 cm deep, failed naturally and two size 3 avalanches were triggered accidentally by snowmobilers just south of the region near Kimberley. Solar warming may lead to another spike in deep persistent slab activity over the next couple of days.
Snowpack Summary
Wind slabs in the alpine and at treeline are becoming less reactive. A melt-freeze crust exists from valley floor into the alpine on solar aspects. A key concern is a persistent weak layer of buried surface hoar from mid-February that is buried 1-2 m deep. Snowpack tests give sudden "pops" results on this layer in some areas, indicating the ongoing potential for very large avalanches. Because the layer is so deeply buried, it's unlikely to fail without a large trigger (e.g. cornice fall or explosive). However, there's always the chance of someone stumbling across a sweet spot, particularly in shallow snowpack areas. Solar warming could also destabilize the overlying snowpack, with the potential for step-downs or cornice triggering on this layer.
Problems
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.