Regions
Kootenay Boundary.
There's a lot of uncertainty around what affect warming alpine temperatures will have. Widespread cornice failure and loose snow avalanches are likely, wind slabs may become more sensitive to triggering too. A cautious approach will serve you well.
Confidence
Low - Freezing levels are uncertain
Weather Forecast
The recent stormy pattern that December begat is history, and we enter a new meteorological regime marked by remarkable stability and a strong temperature inversion with an almost complete void of storminess over B.C for the next week. FRIDAY: No precipitation, freezing level at valley bottom with above freezing temperatures between 1800 and 3000 m, light SE winds. SATURDAY: No precipitation, freezing level at valley bottom with above freezing temperatures between 1800 and 2900 m, light SE winds. SUNDAY: No precipitation, freezing level at valley bottom, light SW winds. For a more detailed look at mountain weather visit avalanche.ca/weather
Avalanche Summary
On Tuesday and Wednesday quite of a bit of slufing/loose dry activity was reported to size 1. These small natural avalanches were running in the upper 10cm of the snowpack. There is a great deal of variability across the region. The southern Monashees reported 40 cm deep soft slabs on Monday that were easy to trigger and entrained loose dry snow in avalanche tracks and runouts. One ski cut stepped down to a weak layer buried about 100cm deep according to a MIN report. (https://bit.ly/1Sn9Do7) As you move east across the region the storm slab depths become less, with about 20 cm in the Rossland range, and closer to 10 cm of recent snow, 40-50 cm of overall storm snow in the Kootenay pass.
Snowpack Summary
The southern Monashees around Big White have reported recent storm slabs up to 40cm in depth that are easy to trigger. Another 5-10 cm of new snow fell on Sunday in the Kootenays, making the weekend total about 10-20 cm of dry cold snow. This snow fell on a variety of old surfaces including small grain facets, surface hoar up to 14mm in size and a sun crust on steep south and southwest facing features. In the last week the region received 40 to 60cm of storm snow that remains largely unconsolidated. Below this snow you will find the mid-December crust. It has not been problematic anywhere yet, but in Kootenay Pass there is a spotty surface hoar layer on or just above this crust. This interface is down around 60cm and the surface hoar is most prevalent on north facing features between 1800 and 2000m. At treeline the early December crust is down around 70 to 120cm. This thick and supportive crust is likely capping any deeper weaknesses in most places. There have been reports of facets on this crust in the Nelson area, so we'll want to keep our eye on it as we move into the New Year. The lower snowpack is thought to be well settled.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.