Regions
Kootenay Boundary.
Although the danger has dropped to CONSIDERABLE, a very cautious approach is imperative. The mountains have hit the reset button and we need to do the same with our expectations of what is safe to ride.
Weather Forecast
Thursday: Expect mixed skies with some sunny breaks later in the day. Temperatures should reach -10 and winds turn to light northerlies.Friday & Saturday: A ridge dominates giving mixed skies, light northerly winds and cool alpine temperatures. Valley cloud is possible.
Avalanche Summary
Avalanches up to 2.5 have been reported, predominantly windslabs failing naturally and with explosives in lee locations. Isolated rider triggering has also been reported.
Snowpack Summary
The recent storm has brought up to 60cm of snow. Consistent southwest winds have redistributed the new snow (dramatically in some areas) to create widespread windslabbing on lee and open features in the alpine and exposed treeline. Where the wind has been strongest, windslabs are much lower on slopes than normal.There have been avalanches reported both within the storm layers as well as at the initial storm interface, the January 4th layer. This layer consists of small facets, surface hoar (up to 12mm) in sheltered treeline and below treeline areas and sun crust on steep south and west facing slopes. The bonds with the facetted snow are improving while the surface hoar &/or sun crust interface is weak. There are reports of Sudden Planar shears (fast & clean) in compression tests and “Propagation Likely” results in extended column tests on the preserved surface hoar.The midpack is well bonded and strong. The November 28 surface hoar is still being found in isolated, sheltered below treeline locations buried 120cm. The deep crust/facet combo from early November still exists and concern remains (although unlikely) for triggering this layer from a shallow spot or with a heavy load.
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.
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.