Kootenay Boundary

Strong outflow winds have generated reports of wind slab formation on all aspects and elevations. Meanwhile, our lingering persistent slab problem continues to produce large, human triggered avalanches.

High -

Monday night: Cloudy with clear periods. Strong northeast winds. Tuesday: Mainly sunny. Moderate to strong northeast winds. Alpine high temperatures around -14.Wednesday: Cloudy with sunny periods. Light east winds. Aline high temperatures around -8.Thursday: Mainly cloudy with isolated flurries and a trace to 5 cm of new snow. Light variable winds. Alpine high temperatures around -8.

Another large (size 2.5) persistent slab was triggered by a skier in the Evening Ridge area on Sunday. It occurred on a southeast aspect at about 2000 metres and featured a crown fracture around 50 cm deep and 350 metres wide. A weak layer from early February is suspected as the failure plane.On Saturday, a few small (size 1-1.5) human triggered slab and loose dry avalanches were reported. One large (size 2.5) naturally triggered persistent slab avalanche was observed on a south aspect near Paulson Summit.Human triggered avalanches were reported everyday between February 12 and 20. Although most avalanches were small (size 1-1.5), some had impressive propagation on buried weak layers (see some examples here and here). Last Tuesday, a notable size 3 persistent slab avalanche occurred on an east aspect at 2000 m. This avalanche was triggered by explosives and failed on the persistent weak layer that was buried on February 7th.

The latest storm brought 15-25 cm of low density snow that now covers variable wind slabs at higher elevations and sun crusts on south-facing slopes. Fresh wind slabs have formed in exposed terrain under the influence of increasing northerly winds.A weak layer of surface hoar (feathery crystals) and a crust that was buried on February 7th is now 30-50 cm deep. This layer has been reactive, and has produced avalanches as large as size 3. Two other surface hoar layers are buried 50 to 80 cm deep the snowpack (referred to as the February 1st and mid-January layers). Although they have not been reactive recently, they are still being monitored by professionals. The lower snowpack is considered generally strong.