Regions
Banff Yoho Kootenay.
With a high pressure system settling into the divide over the next few days, heating will be the critical factor to monitor. Expect a steady heating trend to increase the avalanche hazard toward the weekend.
Weather Forecast
Following the upslope precip that arrived Sunday, forecasts show a large high pressure system pushing into the divide overnight. This should bring a good freeze into Tuesday but freezing levels will quickly return to around treeline with the potential for a trace of precip. A weak freeze into Wednesday, again with a bit of precip as temps rise...
Snowpack Summary
A few cm of new snow today became moist with heating at low elevations and some solar input. Crusts are buried on solar aspects and on shady aspects below 2000m in the upper snowpack. Shallow snowpack areas are weak, and we are concerned about facets in the lower snowpack overlain by a stiff slab which produces easy, sudden collapses in tests.
Avalanche Summary
No avalanches observed or reported today.
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.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.