Regions
Kootenay Boundary.
Confidence
Fair - Due to variable snowpack conditions
Weather Forecast
Saturday: Freezing level starts at valley bottom, rises to 1000m during the day. Strong ridgetop winds out of the NW. No precip expected.Sunday: Freezing level starts at valley bottom, rises to 1000m during the day. Winds start strong out of the NW, backing down to moderate by dinner time. No precip expected.Monday: Freezing level starts at valley bottom, rises to 1000m during the day. Ridgetop winds mod/strong west. No precip expected.
Avalanche Summary
No new avalanche observations from Thursday. On Wednesday numerous wind slab avalanches to size 2 were reported from NE, E and SE facing slopes along with loose wet avalanches to size 1 were also observed on steep solar aspects.
Snowpack Summary
Recent winds have formed hard slabs, soft slabs and sastrugi in open terrain. We've received reports of hard slabs up to a meter deep in the region. South and West facing slopes have been moistening up during the day with the warm temperatures. Protected areas are growing surface hoar to 10mm. Under the moist snow and wind slabs the January 4th layer can be found down 50 - 150 cm. It consists of small facets, surface hoar (up to 12mm) in sheltered treeline and below treeline areas, and a sun crust on steep solar aspects. When tested, the interface produces the full spectrum of fracture characters from sudden planar to no failure at all. Needless to say it's quite varied. The midpack is well bonded and strong.
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.
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.