Regions
Banff Yoho Kootenay.
20-40 cm of light, dry snow has fallen since Wednesday - so far under light wind conditions. The wind will make or break the avalanche danger over the next 24-hours. If the wind picks up - the avalanche danger will rise. Ski conditions are excellent.
Weather Forecast
The current storm pattern is forecast to continue through to Saturday, with daily accumulations of 10-15cm expected. By mid-day Thursday we expect close to 40cm to have fallen over the higher terrain. Wind is forecast to be light in the valley bottoms, and moderate from the west at the ridge top elevations. Temperatures will stay cool (-5 to -13).
Snowpack Summary
20-40 cm of light, dry storm snow has fallen across the forecast area since Wed night. This new snow sluffs easily and runs far on the underlying surface and has been blown into small, but very touchy windslabs in alpine areas. Deeper in the snowpack the Feb 10 layer remains a real concern in shallow snowpack areas such as the Kootenay burns.
Avalanche Summary
One skier triggered size 1.5 avalanche near Sunshine in a steep, alpine chute. Minimal observations due to poor visibility.
Confidence
Intensity of incoming weather systems is uncertain
Problems
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.
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 Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.