Regions
Kootenay Boundary.
Wind slabs are a prime concern these days.
Confidence
Moderate - Freezing levels are uncertain
Weather Forecast
The remnants of a Pacific system will move into the interior early Tuesday. bringing light snow with the possibility of freezing rain very early in the morning on Wednesday. The rain should change to snow late Wednesday morning leaving us with 5 cm of snow. The next Pacific frontal system will move into the area on Thursday.
Avalanche Summary
Reports of skier accidental, skier remote, and skier controlled avalanches, have diminished in the past 24 hrs, but operators are still reporting impressive results with explosives. With the continued moderate South West winds, recently deposited storm snow is still being redistributed on lee features around tree line and above.
Snowpack Summary
Recent snowfall combined with strong ridge top winds formed storm slabs at all elevations these past few days. A rain crust formed at the end of the last storm between 1500 and 2000 metres, and now has 10 to 20 cm of storm snow resting on it. In some area, storm snow is resting on a crust with facets around 90 cm below the surface. These facets may be the remnants of a surface hoar layer formed at the beginning of January. Recent testing has shown this facet layer to be reactive, especially in places with no previous skier or rider activity. It appears to be most prominent at treeline and below, and on all aspects. A melt freeze crust from December buried anywhere from 80 to 130cm across the region is still prominent in the snowpack, but no recent avalanche activity has been reported at this interface, however, it is worth keeping an eye on. Below this, the snowpack is generally well settled and strong.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.