Regions
Banff Yoho Kootenay.
Cooler temperatures forecasted for the next few days with a valley bottom freeze tonight. We should see wet avalanche activity taper off tomorrow.
Weather Forecast
Valley bottom freezing levels forecasted for tonight with clear skies, except for along the Wapta where mainly cloudy skies are expected. Thursday will be a mix of sun and cloud with alpine highs around 0 with light west wind. The couple of days will be cooler than Monday and Tuesday.
Snowpack Summary
Supportive crust on solar aspects in morning which are deteriorating by mid day. High elevation north aspects still have dry snow. Mid pack is well settled with no significant shears. The basal facets remain the main weakness in the snowpack, but we expect only large loads or a dramatic rise in temperatures to cause failures on this layer.
Avalanche Summary
A natural wet slab avalanche cycle occurred on all aspects at treeline and above late Tuesday afternoon and into the evening . Slabs were up to size 3 and were 40-60 cm deep.
Problems
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.
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.
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.