Strong wind, warming temperatures and new snow may create new avalanche problems.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A Pacific front embedded in a southerly flow brings snow (5-20 cm total), strong S to SW winds and freezing levels rising to around 1500 m on Thursday and Friday. Precipitation and winds ease and temperatures drop on Saturday.For more details check out https://avalanche.ca/weather.
Avalanche Summary
On Monday, several small slabs were triggered by skiers, including three that were remotely triggered. These were either on wind-loaded features at and above treeline, or in openings at low elevations, where buried surface hoar is largest and most reactive. These events suggest that there is a very touchy interface, but in general there is not enough load above it to create destructive avalanches. This situation could very quickly change, so watch for any areas with increased loading from wind or snow, and be alert if temperature changes cause the slab to become more cohesive. On Tuesday, skiers who ventured onto a steep alpine feature in a permanently closed area within a ski area triggered a size 1.5 wind slab.
Snowpack Summary
Conditions are variable across the Purcells. Isolated wind slabs are lurking behind ridges and ribs in some areas. 15-40 cm of recent storm snow overlies a mix of surface hoar, facets, and sun crusts that were buried in early January. In many parts of the Purcells, there is not yet a cohesive slab above this interface, apart from in wind-affected areas. In the far west of the region, there may be a deeper and more consolidated slab over the touchy early January interface. Operators are still keeping an eye on a more deeply buried layer of surface hoar from December, which is now considered dormant or unreactive. In general, the mid and lower snowpack are well settled and strong.
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.