Conditions are extremely variable across the region.
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Wednesday: Cloudy with a few snowflakes. Cold (around -18C). Moderate to strong westerly winds. Freezing level valley floor.Thursday: Light snow possible at times. Remaining cold. Friday: The next frontal system is due to hit the region late in the day, bringing moderate-heavy snow, rising temperatures and gusty winds. Freezing level climbing near 1500m by the evening. The timing of this system is uncertain.
Avalanche Summary
Natural avalanche activity was likely to have peaked during the most rapid loading on Tuesday. Fast-running loose snow avalanches were reported. Observations have been limited by poor travel conditions.
Snowpack Summary
Intense snowfall which started on Monday night and persisted through Tuesday, with rates of 5-7cm/hr observed, was centred on the Lizard Range. In the South Rockies region, the Flathead and southern Elk Valley received the most snow (around 30cm), with lesser amounts further east and north. The snow was exceptionally light and dry and has shown little slab properties, but is running easily as fast-moving sluffs. It came with no wind at Castle Mountain and mainly light winds in other parts of the region. Below the storm snow, older wind slabs appear to be well bonded. Expect new wind slabs to develop if the wind rises.Besides new storm/wind-related concerns, the main layer we're watching in the region is a surface hoar layer buried in early December. It's down about 1m in the Flathead and recently exhibited hard, sudden planar/full propagation results, meaning that's it was stubborn to trigger but could create a large avalanche. Facets sandwiched between two firm layers in the top metre of the snowpack are being monitored in the south-east.
Problems
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
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.