Regions
Banff Yoho Kootenay.
Start early and end early! If the sun appears, expect the avalanche hazard to rapidly rise towards HIGH, especially if the winds also decrease.
Weather Forecast
For Saturday and Sunday increased cloud and wind is forecast and will help keep things a little cooler. Freezing levels will only drop to 2000 m tonight and climb to 2400 m Saturday. If the sun comes out expect the avalanche hazard to rapidly rise towards HIGH.
Snowpack Summary
After 2 hot days, expect surface crusts on all aspects (expect high due North aspects) with moist snow underneath. Crusts will rapidly break down with daytime heating or sun exposure. In many places the snowpack is sitting on a deep persistent of facets that has been avalanching to size 3.5 with solar heating over the past 2 days.
Avalanche Summary
Another day of widespread natural activity. Numerous deep persistent avalanches to size 2.5 on N-NW aspects in and loose wet avalanches to size 2 on solar aspects. On Thursday, there were solar induced natural avalanches in Kootenay today to size 3.5 where the sun has been out all day. Many of these were stepping to ground.
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.