Conditions are variable across the Purcells. In isolated areas, the weak layer from early December may still be reactive.
Confidence
Moderate - Wind speed and direction is uncertain
Weather Forecast
A few centimetres of snow are expected on Monday, before a shift to a cool, dry spell. Expect light northerly winds and a mix of sun and cloud on Tuesday and Wednesday.For more details check out https://avalanche.ca/weather.
Avalanche Summary
On Wednesday, two skier accidental avalanches were reported in the Golden backcountry. The first occurred in the morning and was a size 2 wind slab avalanche which occurred on a northwest aspect at about 2400 m. It was up to 50 cm in depth and ran approximately 600 m. The second occurred in the afternoon and was a size 2.5 wind slab at ridgetop. This also occurred on a NW aspect at 2400 m elevation. This avalanche stepped down to a deeper layer lower down in the start zone, likely the early December interface. On Thursday, a large settlement was felt in a flat meadow in the Invermere backcountry. This occurred at 2200 m in a below treeline terrain feature and the failure layer is unknown. Since then, only small loose dry avalanches have been observed.
Snowpack Summary
20-30 cm of low-density snow typically overlies a well-settled mid and lower snowpack. Surface hoar and near-surface facets may be mingled with a few cm dry new snow. Wind slabs may be found on slopes lee to the SW. Between 40 and 100 cm below the surface you'll probably find a weak layer which was buried in early December. Between 1400 m and 1800 m, this layer consists primarily of large surface hoar. At higher elevations, this layer consists of a sun crust, facets, and/or small surface hoar. This layer is still reactive in some snowpack tests and has produced at least one human-triggered avalanche in the last week. The layer is creating a low probability, high consequence type of problem, especially in the north of the region. Below this layer, the snowpack is thought to be generally strong and well-settled.
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.