Regions
Banff Yoho Kootenay.
Avalanche control will be conducted on Mt. Stephen, Mt. Dennis, and on Mt. Hector on Tuesday. Please no skiing or climbing in these areas.
Weather Forecast
A weak freeze overnight with freezing levels rising to 1800m on Tuesday. Some flurries forecasted but little in the way of accumulation.
Snowpack Summary
45 - 70 cm of recent storm overlies a crust from January 30th. The recent heavy precipitation, and warmer temperatures have created very touchy storm slabs over top of the January 30th crust interface. Despite a weak freeze last night isothermal conditions persist at treeline and below.
Avalanche Summary
Avalanche control over the past three days in Banff, Yoho Park and Koorenay Park have produced numerous avalanches up to size 3. Many of the avalanches started dry and turned wet at lower elevations. Also, evidence of a widespread cycle up to size 3.5 throughout the forecast region. Some avalanches running close to full path.
Confidence
Freezing levels are uncertain
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
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.
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.