While the storm has eased somewhat, it isn't over yet. Dangerous conditions remain in the backcountry.
Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
Synopsis: A short-lived lull in precipitation is likely for Saturday, before it resumes Saturday night and into Sunday. By Monday, things should dry out.Friday night: 10-15 cm/mm snow/rain.Saturday: Only light amounts are expected during the day, except perhaps for the far north of the region. Snowfall starting again in the evening. Freezing level dropping from 1500 m in the morning to around 800 m in the afternoon. Winds southwesterly up to 40 km/h.Sunday: 5-10 cm new snow. Freezing level around 900 m. Northwesterly winds to 30 km/h.Monday: Dry, with some good sunshine. Cold in the morning, freezing level rising to 1000 m in the afternoon. Light winds.
Avalanche Summary
A widespread avalanche cycle occurred on Friday with preliminary reports of avalanches running up to size 4. Avalanche activity appears to have been more pronounced in the north of the region. Due to the lack of observers in the mountains today, details are limited at this time.
Snowpack Summary
A heavy dump of moist new snow has added to recent storm totals (now 120-150 cm over a two-week period). The snow surface became wet as snow gradually turned to rain to approximately 1800 m. As temperatures drop, expect to see a crust form at lower elevations. Below the storm snow lies a highly reactive weak layer of surface hoar layer (and/or a crust) which was buried on February 12th. Strong southwest winds have redistributed the new snow into deep wind slabs on exposed lee slopes and cross-loaded gully features. The February 12 layer is primed for triggering and has been reacting readily to both natural and human triggers on all aspects and a wide range of elevations. Deeper persistent weak layers from early February and late January continue to show planar failures when moderate to hard forces are applied in snow pack tests. In particular, in the Monashees, a rain crust buried at the end of January approximately 150 cm has been responsible for a couple of recent large, surprising avalanches. During, or immediately following the current storm, the presence of deeper weak layer could further increase the potential size of avalanche events.
Problems
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.
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.