Natural avalanches possible, human triggered probable.
Alpine
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 possible, human triggered probable.
Regions
Banff Yoho Kootenay.
Natural activity is still occurring and the potential for very large human triggered avalanches on the weak facets remains high. Avoid exposure to overhead hazard and stick to moderate angled supported terrain to enjoy the new snow.
Weather Forecast
The ridge will break down on Tuesday as clouds and flurries with warmer temperatures push into the region in the afternoon. Flurries with warmer temperatures and freezing levels around 1850m will continue for Wednesday before a cooling trend returns. Alpine temperatures should remain below freezing. Winds will be moderate out of the SW.
Snowpack Summary
40 to 80 cm of storm snow with SW winds in the last two weeks has helped create a thick supportive slab over the deep weak basal facet layer. Rain to 2000m on Saturday created a surface rain crust which is now frozen and covered by new snow, and saturated the lower elevation snow. Sudden collapse results in the basal facets continue in test pits.
Avalanche Summary
Natural activity to size 3+ was observed again today in Yoho and Banff. Both natural and explosive control work in the last several days has produced massive results in the Lake Louise and Yoho regions with impressive propagation. Many large avalanches have run to the bottom of their run outs entraining moist snow at lower elevations.
Confidence
Freezing levels are uncertain on Wednesday
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.