Regions
Kootenay Boundary.
The avalanche danger will gradually increase through the end of the week into the weekend as forecast precipitation amounts begin to accumulate
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Friday
Weather Forecast
THURSDAY: Mix of sun and cloud / Light south wind / Alpine temperature -4 / Freezing level 1300mFRIDAY: Flurries, accumulation 5-10cm / Moderate southwest wind / Alpine temperature -3 / Freezing level 1300mSATURDAY: Flurries, accumulation 5-10cm / Moderate southwest wind / Alpine temperature -4 / Freezing level 1400m
Avalanche Summary
Reports from Tuesday indicate snowballing and loose snow avalanches to size 1 from steep terrain on all aspects from tree line and below.
Snowpack Summary
Last weekend rain soaked the upper snowpack for a second time in a week all the way to mountain tops. Subsequent cooling temperatures then formed a 10-30cm rain crust. In many parts of the region above the 1500m there may now be 10-15cm 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.