Regions
Kootenay Boundary.
Confidence
Fair - Intensity of incoming weather is uncertain on Tuesday
Weather Forecast
Synopsis: The ridge of high pressure that has brought clear weather starts to erode and allows a frontal system to move in, bringing precipitation on Tuesday.Monday: Dry until late in the day, with increasing cloud cover through the day. Freezing level around 600m in the afternoon. Light westerly winds.Tuesday: Around 5cm new snow. Freezing level around 1400m in the afternnon. Westerly winds gusting to 70 km/h at ridgetop.Wednesday: Flurries or light snow in the morning, dry in the afternoon. Freezing level 1000m in the morning, dropping to valley bottom by the afternoon. Moderate NW winds.
Avalanche Summary
There were two size 1 human-triggered avalanches reported from Saturday on north aspects in recent new snow with crowns of 10-20 cm. Loose snow avalanches were reported over the weekend on steep solar aspects.
Snowpack Summary
The snow surface consists of a sun crust, surface hoar, or a dusting of new snow. Below this approximately 15-20 cm of recent storm snow has been redistributed into soft wind slabs at higher elevations. The new snow overlies a gamut of old surfaces which include old wind slabs at higher elevations, fairly widespread surface hoar, and a melt-freeze crust on previously sun-exposed slopes. This interface will be something to watch as the overlying slab develops. About 35-50cm below the surface is another interface of surface hoar or a sun crust that was buried on Jan 23. It is hard to find in some areas and seems to be gaining strength where it is found, but this weakness is still on the radar of professionals in the region. The snowpack below this is generally well settled and bonded.
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.
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.