Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Banff Yoho Kootenay.
http://www.pc.gc.ca/apps/scond/Cond_E.asp?oID=19299&oPark=100092Tricky conditions continue. Cooler temperatures are on the the way, but it will take time for the snowpack to become less reactive. Solar input Sunday will augment the snowpack problems. SH
Weather Forecast
We are looking at a cooling trend (finally!) starting Sunday. Temperatures will go below -10C in the alpine and -6C at valley bottom. A mix of sun and cloud with light gusting moderate N-NW winds. Seasonal temperatures will persist for the next few days.
Snowpack Summary
10-20cm new snow up Hwy. 93N with drizzle and rain in other regions Saturday morning. 60-70cm of well settled snow from recent balmy temperatures sits over weaker facets and depth hoar in the bottom portions of the snowpack. A snow pit done at 2350m on Cirque peak demonstrates the snowpack layering common throughout the forecast region.
Avalanche Summary
Lots of natural activity to size 3.5 with wide propagations (hundreds of meters) stepping to ground. Most of these were triggered by fresh wind loading by N winds accompanied by solar effect. Over the last 2 days there have been notable skier triggered avalanches which stepped down to the basal weak layers. See here for photos of today's events.
Confidence
Due to the number of field observations on Saturday
Problems
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.