Regions
Kootenay Boundary.
Weather Forecast
THUR: A dirty ridge hangs over much of the region today bringing cloudy skies and the occasional convective flurry. I'm only expecting a few cm's Thursday, even in the most favored valleys. The atmosphere stabilizes Thursday evening & 2000m temps drop down to - 16 overnight. FRI: Friday dawns cool & cloudy, but, it is a day of change in the pattern. Freezing levels rise to 1000m as the ridge flattens late in the day. Snow should start up around supper time & but only 2 - 5 cm are expected to be on the ground when we wake up Saturday. SAT: Saturday offers occasional snow flurries with a daytime total of 5cm or so. Freezing level will continue to rise to 1500m. SUN: Precip should pick up in intensity Sunday, but the freezing level is forecast to be quite high, near 2000m, so most of the precip will fall as rain on everything but the highest peaks. 5mm of water is expected Sunday. The precip shuts down Monday and temps drop back down to seasonal norms. 2000m Wind: Thur: L, NWFri: W, Mod, G StrongSat: W, StrongSun: Strong W, switching Strong SW midday.
Avalanche Summary
The majority of the activity yesterday was in the form of loose snow avalanches to size 1.5 in steep, open terrain. Two size 2 - 2.5 avalanches were reported in the Bonnington range, on E & W aspects, both were remote triggered, failing on the Feb. 08 SH.
Snowpack Summary
5 cm of snow has fallen as of 3:00pm Wednesday. This new snow is falling on surface hoar on shady aspects and a thin sun crust on solar aspects which will keep the sluffing problem alive in steep open terrain. The big story continues to be the buried surface hoar, now down 60 - 120 cm below the snow surface. Avalanche activity on this layer has slowed a bit, but it is still producing. When it goes, it goes big. This layer is growing more stubborn, but it is still more than capable of producing avalanches to size 3 which by definition are big enough to destroy a car or woodframe house. Professionals throughout the region are treating this layer with extreme caution, since it is showing signs of remote triggering and the ability to propagate in low angled terrain. In the alpine there may be enough wind to create new windslabs that are softer and probably will not bond well to the old surface.
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.