A Special Public Avalanche Warning is in effect for this region.
Weather Forecast
The next three days look cool and dry, with sunny spells. The freezing level is around 1400 m on Sunday, falling to valley floor overnight as a strong ridge sets up. It is expected to get into a diurnal cycle after that (falling to valley floor at night and rising by day to around 1200 m). Winds are generally light from the NW.
Avalanche Summary
A warming-related natural avalanche cycle occurred on Thursday and Friday. Many cornices also collapsed naturally and with explosives over the last few days, occasionally triggering slabs on the slopes below. Skiers triggered a very large (size 3.5) persistent slab on Thursday on a NE aspect in the alpine in the Monashees. It failed on the late-Jan layer. Avalanche activity is likely to taper off with cooling temperatures, but large avalanches remain possible, and sun may cause another spike in avalanche activity on steep solar aspects.
Snowpack Summary
As the weather finally cools after ten days of very warm temperatures and bursts of rain, surface crusts are likely to form. Underneath newly formed crusts, you may find moist snow for a few days yet. At alpine elevations, new wind slabs or storm slabs may be found. Cornices may be large and weak. The late-Jan crust/surface hoar layer, buried up to a metre deep, remains a key concern. Recent avalanches on this layer have been very large. The mid-January surface hoar is typically down 80-120cm and is most likely to be triggered from thin or rocky snowpack areas; or perhaps with a cornice fall, or an avalanche stepping down. The mid-December weak layer is down over 120cm, but is generally considered unreactive.
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.
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.