Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Kootenay Boundary.
A Special Public Avalanche Warning is in effect. Copy this link to view details: http://bit.ly/2nSOUyX
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Tuesday
Weather Forecast
MONDAY: Mainly sunny, with increasing clouds late in the day. Light winds. Treeline temperature near -10.TUESDAY: 5-10 cm snow. Light to moderate westerly winds. Treeline temperature near -5.WEDNESDAY: Flurries. Light winds. Treeline temperature near -8.More details can be found in the Mountain Weather Forecast.
Avalanche Summary
A widespread avalanche cycle occurred this week on all aspects and elevations. Persistent slabs up to size 3 were observed during the peak of the storm loading on Thursday. On Friday and Saturday, natural activity slowed down, but large explosive and machine-triggered avalanches continued to be reported.The natural cycle has wound down, but human-triggering remains a real concern. You might be surprised by how large an avalanche can be triggered and how far it could run.
Snowpack Summary
Storm snow accumulations from the past week vary from 10-45cm across the region at upper elevations. In the alpine this new snow has been redistributed to leeward slopes from strong northwest winds. Fragile cornices may be found at ridge top. Below 1850 m, around 5 cm of low density snow covers a hard crust. This now brings 1- 2 m of settled snow sitting on three significant surface hoar/ crust layers that were formed early to mid-January, and back in December. Near the base of the snowpack a crust/ facet interface exists that will likely haunt us all season. These persistent weak layers that lurk within the snowpack are reactive, producing large and destructive avalanches. The snowpack is extremely complex and requires respect and diligence at this time.
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.