Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Regions
Cariboos.
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
An Arctic air mass keeps things cold and dry until Tuesday, when moderate snow is expected, with milder temperatures and strong south-westerly winds.More details can be found in the Mountain Weather Forecast.
Avalanche Summary
A very large, widespread avalanche cycle was observed on Thursday and Friday. Slopes of all aspects and elevations ran full path and reached valley floor. In some cases, mature trees were smashed. Many of these failed on persistent weak layers, while some involved only the recent storm snow. The natural cycle is winding 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
Strong north to north-westerly winds have loaded lee slopes with 30-40 cm recent storm snow. This adds to an existing storm slab up to 1m deep from the last couple of weeks accumulation. Several persistent weak layers make up a troublesome snowpack which is not tolerating the recent load. In the top 1-1.5 m of the snowpack, two surface hoar layers buried in January can be found. The shallower of the two has been particularly reactive on north to east aspects above 1900 m, but expect to find one or other of these on all aspects and elevations.Deeper in the snowpack (120-200 cm deep) is a facet/crust/surface hoar layer from December, most prevalent at and below treeline.Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.All of these layers have produced large avalanches recently. The wide distribution and ongoing reactivity of these layers suggests that avoidance through choosing simple terrain is the best strategy.
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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.