Regions
Banff Yoho Kootenay.
http://www.pc.gc.ca/apps/scond/Cond_E.asp?oID=34810&oPark=100092 The diurnal avalanche cycle prompted by day time heating continues. Avalanches are starting to dig deeper at lower elevations. Time your trips be done by noon or before the avalanche activity starts as the crusts break down...
Weather Forecast
Expect similar weather tomorrow with generally clear skies again tonight to help freeze the snowpack despite the relatively warm overnight temperatures. Conditions will deteriorate rapidly Thursday with daytime heating. Temperatures at treeline will climb to 10-15C. Temperatures will cool Saturday as the ridge moves east allowing cloud to move in.
Snowpack Summary
Sun crusts or moist snow on solar aspects and isothermal snow at lower elevations. Above treeline, 10-50 cm of recent snow sits over a mix of facets, sun crust and wind slabs. While a supportive mid-pack exists in thicker areas, very weak facets to the ground are seen in many thinner areas.
Avalanche Summary
A widespread spring avalanche cycle continues with the bulk occurring on solar aspects as they heat up through the day. Avalanche size ranged from size 1-3. Most slides have been within the surface snow (March 7 interface) with some stepping down a bit deeper; however, we have seen only a few avalanche step down to the basal layers.
Confidence
Due to the quality of field observations on Wednesday
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.
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.