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
A mix of sun and cloud for Saturday with moderate northwesterly winds and alpine temperatures around -10. Sunday should be mainly cloudy with flurries bringing around 5 cm of fresh snow by the afternoon. Ridgetop winds are expected to increase to moderate to strong westerlies and alpine temperatures around -10. Expect to wake up Monday morning with 5-10 cm of fresh snow in the mountains with an additional 5-10 cm throughout the day all falling under strong southwesterly winds. Temperatures are expected to warm considerably, but freezing levels should remain in valley bottoms
Avalanche Summary
No new avalanches were reported on Wednesday or Thursday. 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.