Regions
Banff Yoho Kootenay.
The main concern right now is daytime heating. Start and finish early to take advantage of the colder temps and reduced avalanche hazard in the mornings. Some lingering concerns for deeper weak layers also exist as we transition to spring conditions.
Weather Forecast
A mix of sun and cloud for Friday and Saturday will bring slightly warmer temperatures and increased solar inputs. Day time highs for Friday will reach +7'C at valley bottoms but stay below freezing in the alpine. Forecasted winds are generally light. We currently expect a cooler cloudy day on Sunday.
Snowpack Summary
10-20 cm of recent snow overlies a variety of surfaces depending on aspect and elevation. A supportive melt freeze crust is present below the new snow in most areas excluding high north aspects. Many areas have a cohesive mid-pack over the basal facets, while thin areas often have weak facets to ground. Lower elevations are becoming isothermal.
Avalanche Summary
Loose dry avalanches up to size 1.5 were observed above treeline on Wed/Thurs following the arrival of the new snow on Wednesday. There have been a couple isolated size 1.5 to 2 slab avalanches in the last several days running on buried facets in thin snow pack areas. This activity has slowed down with cooling but the weakness persists.
Confidence
Timing or intensity of solar radiation is uncertain on Sunday
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.
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.