Regions
Kootenay Boundary.
Fresh and touchy wind slabs are building in unusual places. Use caution as you transition into exposed terrain.
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
On Friday expect a mix of sun and cloud with light to moderate northerly winds and alpine temperatures in the -15 to -20 range. Mainly cloudy for Saturday with moderate to strong northwesterly winds and alpine temperatures around -15. Sunday should also be mainly cloudy with a chance of flurries late in the day. Ridgetop winds are expected to increase to strong westerlies and alpine temperatures increasing to -10.
Avalanche Summary
No new avalanches were reported on Wednesday. Reports from Tuesday are limited to natural and rider-triggered sluffs up to Size 1.5. 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.
Snowpack Summary
Around 30cm of faceted powder overlies the facets and surface hoar that was buried last weekend. Variable light to moderate winds have loaded immediate leeward features with touchy wind slabs. A widespread crust that was buried in November is typically down 80-100cm. Recent tests show this persistent weakness has the propensity to propagate large avalanches if triggered, from thin rocky areas, for instance.
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.