Regions
Banff Yoho Kootenay.
Mainly cloudy skies should keep heating to a minimum at upper elevations but watch for daily heating to break down crusts below treeline where recent heating has weakened the snowpack.
Weather Forecast
Strong solar heating on Sunday added heat to the snowpack. A decent refreeze was found Monday morning and while heating was progressing rapidly at first, snow squalls moving though some areas turned this around. Expect another 5 to 10 cm by the end of Tuesday and mainly cloudy skies through Thursday which will hopefully keep heating in check
Snowpack Summary
Up to 10 cm overnight and today brought by local squalls. At treeline and above, melt freeze crusts exist to ridge top on solar aspects, while on north aspects, dry surface snow still exists above ~2300m. Below 2000m the snowpack becomes wet during the day and is becoming isothermal. The weak basal facets remain a concern mainly in alpine areas.
Avalanche Summary
Sunday, Forecasters received a report of a party of 2 being involved with a size 2 avalanche that was cornice triggered in a N facing couloir by Boom Lake. Both party members were caught by snow that the cornice entrained, and partially buried. One skier was carried further than the other and sustained minor injuries and a lost ski pole.
Problems
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.
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.