Kootenay Boundary

Ch-ch-ch-ch Changes in the weather will add to the size and reactivity of the existing storm slab.

Moderate - Intensity of incoming weather systems is uncertain on Wednesday

On Tuesday expect overcast skies and trace amounts of new snow. By late Tuesday afternoon, steady snowfall will develop and continue until Thursday morning bringing up to 20cm of new snow. Ridgetop winds associated with the system will be strong and southwesterly. Freezing levels may peak at about 1200m on Wednesday, but should otherwise remain at or near valley bottom for the rest of the forecast period.

Over the past few days we've received a quite few reports of skier-triggered storm slabs in the size 1-2 range from the Nelson area. In one case, a size 2 storm slab was remotely triggered from a distance of 5 metres. Recently buried surface hoar was the suspected culprit in all of these avalanches. Storm slab avalanches are expected to increase in size and reactivity with snowfall forecast for later in the week.

20-40 cm of snow fell last week. In some areas this snow exists as low-density powder, while in other places warm temperatures and wind have encouraged the formation of a cohesive slab. The recent snowfall is resting on a widespread layer of surface hoar which overlies a melt-freeze crust on solar aspects or facets in shaded areas. This critical layer, which was buried at the beginning of January, is one to watch as the overlying slabs get deeper with forecast wind and snowfall.About 60-80 cm below the surface, you might find a rain crust from mid-December which co-exists with facets in some areas. Recent snowpack tests suggest that it could still be capable of producing human triggered avalanches. The snowpack below this layer is generally strong and well-settled.