Regions
Kootenay Boundary.
Rising freezing levels through the day on Tuesday may begin to break down the recently formed rain crust. As the crust gradually breaks down it will be important to be increasingly cautious as deeper buried weak layers may become reactive again.
Confidence
Moderate - Freezing levels are uncertain on Tuesday
Weather Forecast
TUESDAY: Cloudy with scattered wet flurries / Light to moderate east wind / Alpine temperature 2 / Freezing level 1000m rising to 2400m by late afternoonWEDNESDAY: Flurries, accumulation 5cm / Light to moderate southwest wind / Alpine temperature 1 / Freezing level 1900mTHURSDAY: Mix of sun and cloud / Light to moderate south wind / Alpine temperature -4 / Freezing level 1400m
Avalanche Summary
Since the cooling weather trend there have been no reports of significant avalanche activity. That being said reports are still rolling in about the extent of avalanche activity during the rain event. Numerous large natural avalanches including size 3 and 3.5 persistent slabs were reported throughout the region failing on deep persistent weak layers at a variety of elevations and aspects.
Snowpack Summary
Last weekend rain soaked the upper snowpack for a second time in a week. This time all the way to mountain tops. Cooling temperatures will have formed a 10-30cm rain crust on the surface. In parts of the region there may now be a thin layer of new snow sitting on top of the crust. Below the crust expect to see moist or wet snow. The late-February facet / surface hoar interface (70-120 cm deep), the mid-February crust (90-130 cm deep), and basal facets in shallow snowpack areas may still be present at upper elevations and may still be reactive and become a concern as surface crusts break down with daytime warming.
Problems
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
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.