Regions
Kootenay Boundary.
The region will be under the influence of a major warm-up through the weekend. Be aware of snow conditions changing quickly and avalanche danger rising.
Weather Forecast
Spring-like conditions persist through the weekend with clear sunny, very warm temperatures during the day, then cooling at night. Alpine temperatures are expected to reach above zero degrees and little wind is forecast.Friday: Few clouds. Alpine temperatures reaching 4.0 degrees. Freezing levels rising to 2200 m in the afternoon then dropping 800 m overnight. Ridgetop winds will blow light from the West.Saturday: Few clouds. Alpine temperatures reaching 5.0 degrees. Freezing levels rising to 2400 m in the afternoon then dropping to 1000 m overnight. Ridgetop winds blowing light from the West.Sunday: Mostly sunny. Alpine temperatures -2.0. Freezing levels 1600 m and then falling to valley bottom overnight.
Avalanche Summary
On Wednesday, numerous loose wet avalanches up to size 2 were reported East through West aspects at all elevations.from Be aware of overhead hazards such as cornice fall. It is likely that natural loose wet, or wet slab avalanche activity will persist through the weekend.
Snowpack Summary
Large cornices loom over many slopes. Cornice fall can act as a large trigger on slopes below, and may trigger a deeper instability if it exists. The upper 10 cm of surface snow has become moist up to 2300 m, and melt-freeze crusts exists on solar aspects. On Northerly aspects surface hoar (up to 12 mm) and surface facetting is occurring.A cohesive slab overlies an old crust (down 50-60 cm) which exists up to ridge top. The crust appears to have gained some strength in most places, and some test results are showing resistant planar fracture characteristics. This layer may be harder to trigger, but should remain on your radar. It may be triggered by larger loads or skiers or riders hitting the sweet spot from a thinner snowpack area. With the weekend warm-up, wet slab avalanches may initiate naturally on this crust. Deeper down, another buried surface hoar layer sits approximately 80 cm. In some places it may not be a concern due to the thick supportive crust that lies above it. Because snowpack variability exists, it is important to dig down and test weak layers before diving into your line.
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
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.