Strong SW winds are expected to form fresh wind slabs. These slabs will likely remain sensitive to human triggering for the next couple of days at upper elevations.
Confidence
Moderate - Wind speed and direction is uncertain
Weather Forecast
The South Coast is receiving an absolute lashing from two storms that are expected to impact the coast Sunday and then again Monday. A bit of that energy should trickle into the Southern Rockies, unfortunately it will mostly be in the form of strong SW winds. SUNDAY: Continued strong SW winds, 1 to 5cm of snow, freezing level topping out at 500m. MONDAY: Strong SW winds, trace of snow, freezing level around 500m. TUESDAY: Moderate SW winds, 1 to 3cm of snow, freezing level at valley bottom. For more detailed mountain weather information visit: avalanche.ca/weather
Avalanche Summary
No new avalanche activity to report from the South Rockies. In the neighboring Lizard Range, control work on Friday produced widespread 10 to 15cm thick wind slabs that ran as large as size 1.5 on a variety of aspects above 1800m.
Snowpack Summary
The series of recent storms has left us with 40 to 60cm of new snow sitting on the December 8th rain crust. For the most part, the new snow has bonded well to this rain crust. It is thought that this rain crust is "capping" the more deeply buried weak layers in the snowpack meaning that for the most part, the weight of riders isn't penetrating below this crust. A weak layer formed in the first few days of December consisting of crust, surface hoar, and/or facets can be found down 70-90cm. Around 20-30cm below this interface is a rain crust from mid-Nov with a thick layer of facets below it. While these two weak layers are thought to be "capped" in most locations, these layers may still be reactive to heavy triggers such as cornices, a rider hitting a big drop into a slope below, or a smaller avalanche in motion.
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.