Regions
Kootenay Boundary.
Fresh and touchy wind slabs are lurking in unusual places. Use caution as you transition into exposed terrain.
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
Expect continued cold and dry conditions for Wednesday, Thursday and Friday with the chance of some cloud Thursday and Friday. Winds should remain light and variable for Wednesday and Thursday, but pick up to moderate northerlies again on Friday. Alpine temperatures are expected to remain in the -15 to -20 range with a weak inversion on Wednesday, but significant cooling for Friday.
Avalanche Summary
Reports from Monday include sensitive ridgetop wind slabs with numerous Size 1's with ski cuts. Elsewhere, explosives control produced limited results with a few Size 2 slabs that likely ran on the late November rain crust. On Sunday, numerous natural and skier triggered size 1-1.5 storm slab avalanches were reported on all aspects near Kootenay Pass. If the winds pick up to moderate, expect to find fresh wind slabs in lee features below ridgetops.
Snowpack Summary
Around 15-25cm of fresh snow recently buried the weak surface hoar and surface facets that formed last week. The new snow is expected to bond poorly to the old interface on it has settled into a cohesive slab, but is reported to be low density and appears to only be a concern in wind loaded features at the moment. The lower snowpack is settled and strong. A widespread crust that was buried in November is typically down 80-100cm. Recent tests show the layer is unreactive but cold temperatures have promoted facet growth around the crust and this layer could become a problem in the future.
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.