Regions
Kootenay Boundary.
If the riding is good, the snowpack stability might not be.
Confidence
Fair - Due to the number of field observations
Weather Forecast
Mainly cloudy and dry for most of the day on Wednesday with light snow starting in the evening and continuing all day Thursday before picking up on Friday with 5-10 cm expected by Friday evening. temperatures are expected to gradually increase throughout the forecast period with daytime highs nearing zero degrees in valley bottoms by Friday. Ridge top winds should remain light from the southwest.
Avalanche Summary
There we no new reports of avalanches on Monday or Tuesday morning.
Snowpack Summary
Surface hoar is growing on a thick hard supportive rain crust that extends as high as 2100 m. Sun-exposed slopes are undergoing daily surface melt-freeze cycles, while shady slopes have a skiff of dry snow on the crust. Critical slopes are high elevation north aspects where facets or buried surface hoar from earlier in the month may be lurking under dense storm slabs, and older facet/crust weaknesses may be persisting. Recent snowpack tests at 2050 m in a NW aspect in Kootenay Pass produced moderate sudden results down 35 cm under the late-November crust and down 79 cm on facets above the early-November crust. Meanwhile in the Southern Purcells, snowpack tests gave easy sudden planer results on well preserved surface hoar where it was found down 30 cm on high north aspects.
Problems
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.