Kootenay Boundary

A warm, wet and windy storm forecast for Thursday will cause the Avalanche Danger to rise throughout the day. Loading from rain and snow will add stress to a touchy layer buried deep in the snowpack.

Moderate - Intensity of incoming weather systems is uncertain on Friday

Around 20cm of new snow is expected to fall between Thursday night and Friday afternoon, although localized accumulations of up to 30cm are possible along the US boarder. Continued snowfall on Saturday may bring up to 10cm of new snow while a developing ridge should allow for mainly sunny skies on Sunday. Ridgetop winds will be mainly strong and southwesterly on Friday becoming light by the weekend. Freezing levels may climb as high as 1700m by late Friday, and then drop to about 1000m by the weekend.

Recent storm loading promoted explosive and human-triggered storm slab activity to size 2.5 on a variety of aspects in higher elevation terrain. In some cases, avalanches were triggered within the storm snow and then stepped down to the early January surface hoar layer. With forecast snow and wind, storm instabilities are expected to continue. Continued loading will also add mass and sensitivity to the deeper early January persistent weak layer. As the overlying slab gets thicker, avalanches at this interface will become larger and more destructive.

Continued moderate snowfall and strong ridgetop winds are expected to form new storm slabs at all elevations on Friday. 50-85 cm below the surface you'll find a weak layer of surface hoar and a hard crust on steep solar aspects. This layer, which formed at the beginning of January, seems variably reactive. Some test results suggest an improving bond at this interface while remote triggering and reports of whumpfing show this layer is still very sensitive to light loads in many areas. I would be increasingly wary of this potentially destructive layer at treeline and below where it has been reactive on all aspects. Up to 120cm below the surface, a melt freeze crust from December is still producing sudden results in snowpack tests. No recent avalanches have been reported at this interface; however, it is worth keeping an eye on with forecast warming and continued storm loading. Below this, the snowpack is generally well settled and strong.