Regions
Kootenay Boundary.
The Special Public Avalanche Warning has been extended. Stay cautious and be conservative in your terrain selection.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Friday
Weather Forecast
An above freezing layer has pushed into the Interior ranges and will persist through Thursday allowing for a strong alpine temperature inversion. Alpine temperatures will be near -5 and below treeline temperatures will be near -13. Ridgetop winds will be moderate from the north-northwest. Friday will bring change in the weather pattern. Confidence in model agreement is poor with precipitation and wind values, however; it looks like we could receive 5 mm, accompanied by strong west-northwest winds.
Avalanche Summary
Avalanche observations on Tuesday showed explosive triggered persistent slab avalanches failing up to size 3 mostly on N-NE aspects from 2000-2200 m. We continue to get reports of skier-triggered, and remotely triggered slab avalanches up to size 2 Check out the new Mountain Information Network observations for a more detailed report. This layer remains touchy to light loads, like YOU.
Snowpack Summary
Up to 35 cm of light, low density snow overlies recently formed surface hoar. Strong northerly winds have transported the new snow onto southerly aspects creating stiff and reactive wind slabs. Up to 80 cm below the surface, a touchy weak layer of surface hoar sitting on a thick rain crust exists. This widespread weak persistent layer consisting of surface hoar/ facets and a hard rain crust was buried mid-December and continues to produce whumpfing and sudden planar characteristics in snowpack tests. Although high elevation slopes may not have the rain crust, they are still reported to have touchy buried surface hoar. At the base of the snowpack, a crust/facet combo appears to have gone dormant for the time being.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.