Conditions are highly variable across the region.
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period
Weather Forecast
Friday: A brief ridge of high pressure brings dry, stable and cool conditions until the afternoon, when the next weather system approaches, bringing moderate snowfall overnight, especially to the north of the region. Saturday/Sunday: Moderate snow in the north and west, with less in the south. Each day, about 20cm or so is forecast near Revelstoke, and about 10cm further south. Strong westerly winds all weekend. Freezing level gradually rising and peaking at 2000m on Sunday.
Avalanche Summary
Avalanche activity has begun to slow, with avalanche size and frequency decreasing. However, a number of avalanches are still being triggered remotely (from several hundred metres away) and accidentally by skiers and machinery. These avalanches are failing on upper snowpack persistent and storm snow weaknesses, on almost all aspects and elevations. Human-triggering of destructive avalanches remains a distinct possibility, while in-your-face clues of instability have diminished. Avalanche activity is likely to increase again this weekend with incoming weather.
Snowpack Summary
In the west and south, 10-15cm of snow fell overnight Wednesday, which may have created localized new storm slabs. For the rest of the region, 60-140cm of recent storm snow is slowly settling above the Feb 16. surface hoar layer and the early Feb interface. A storm snow weakness down about half a metre is touchy in some areas. The early Feb interface consists mainly of surface hoar (widespread) or a melt-freeze crust (on solar aspects). These layers are still touchy, with remote triggers reported each day and full propagation in snowpack tests. It is challenging to pin down exactly where you are most likely to trigger these persistent weaknesses. Wind slabs are now buried by a few cm of snow and bury the upper snowpack weaknesses deeply in places. Large cornices loom as potential triggers for deep avalanches.
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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.