Avalanche Forecast

Poor - Due to limited field observations

Snowfall forecast for the region on wednesday night bringing accumulations of 15-20 cms and moderate to strong ridgetop winds from the sw. Unsettled weather will follow on thursday before an arctic front moves south in to the region bringing light flurries and easing alpine winds for friday and saturday. Temperatures expected to remain at our around surface.Although confidence in the forecast is good for wednesday and thursday, weather models conflict for friday and saturday. Stay tuned for more info.

The weekend storm produced a decent cycle in many regions of the province. The action included wind and storm snow activity in practically all regions. Slides on surface hoar and crusts were recently reported in much of the Columbias and yesterday there was a cycle in the Lizard Range associated with basal facets. Slides up to size 2 or 2.5 were reported with crowns of up to 100cm in windloaded areas and decent propagations in many locations. Wind slab avalanches were occurring at ridge-crest in the Nelson area but the ones reported were small (size 1). While things are slowing down continued activity is expected for a couple of days, especially in windloaded areas. If more snow and wind arrives as is forecast another round of avalanche activity is likely to occur, and the size of avalanches in the Kootenay-Boundary might increase as more snow accumulates and winds blow it around. Check the weather forecast section for details on expected timing and intensity of the next system.

I have no detailed snowpack information for this region other than snowpack depths are likely in the 50-70cm range at about 1600m and a metre or so at 2000m. The following information is an overview of conditions in nearby regions which may provide some insight into what's happening in the Kootenay-Boundary. Below 1200m or so most areas do not have enough snow to produce avalanches except perhaps in isolated, shady spots where the wind has deposited pockets of deeper snow on smooth terrain. Above 1200m, average snowpack depths range from 80-150cms or so at lower elevations and areas that got less new snow over the weekend, to well over 200cms at upper elevations and in areas that got a bigger dump over the last few days. In the upper snowpack, windslab and storm snow instabilities exist within storm snow accumulations of up to 80cms+. These layers were active over the weekend but are now likely starting to settle out in most areas. The mid-pack may contain a melt-freeze crust in areas that had a warm spell earlier in the season and/or surface hoar. The surface hoar especially was very active last week, but reports from yesterday suggest it may be starting to settle out. Haven't heard much about the crust lately. Some locations reported a rain-soaked layer at the bottom of the new snow that fell over the weekend; we don't know much about this layer but it'll be one to watch in the future as it freezes up-it's a classic setup for a facet-on-crust layer. As far as the deep pack goes, basal facets have been reported in the Lizard Range and the Purcells. This layer is currently very reactive in the Lizard Range. If you are seeing action near the ground in other areas, this is the likely culprit. Most other regions report fairly solid basal layering. There's bound to be variability throughout the region and one slope/mountain/drainage may differ significantly from the next. A conservative approach combined with careful investigation of local conditions is advised until we get a better understanding of conditions. Anticipate increased slab development and avalanche activity with snowfall and wind forecast for wednesday night.