Regions
Banff Yoho Kootenay.
A widepread avalanche cycle continues where large avalanches are running well below treeline into snowfree bushy runouts. There is no overnight recovery. It's time to AVOID ALL AVALANCHE TERRAIN AND RUNOUTS. The hazard will remain HIGH to EXTREME.
Weather Forecast
Freezing levels remaining at 3600 m overnight, will cool only slightly on Friday remaining at 2800-3000 m through the weekend with showers and rain forecasted. Winds will be generally light from the SW.
Snowpack Summary
Moist surface snow and a variety of melt freeze crusts in the alpine. Unsupportive isothermal conditions exist at treeline and below. The basal weakness persists in the alpine and is reactive to large triggers and the current warm weather, 3600 m freezing level, & solar input.
Avalanche Summary
Today there were numerous large natural and explosive controlled size 3-4 wet avalanches. Avalanches are running far into below treeline terrain and may affect some hiking terrain. It's a good time to AVOID AVALANCHE TERRAIN completely and pull out the bike and rock gear!
Problems
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.
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.
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.