Regions
Banff Yoho Kootenay.
What a start to the ski season! Forecasters almost think they live somewhere else. Give the snowpack some time to settle to the new load. It's been a lot of snow in a short period of time. SH
Weather Forecast
Cooler temperatures for Thursday and Friday with valley temps between -10 to -12 and alpine temperatures in the -18 to -25 range. Only trace amounts of snow are expected over the next 2-3 days with light to moderate W to NW winds.
Snowpack Summary
Essentially 2 major snowfall events in the past week has created the snowpack. The latest one from Tues threw down 30-50cm low density snow in most areas. There is a fairly supportive midpack, but inconsistent results are still being found within the storm snow, and in some circumstances, near the ground. HS at treeline is well over a meter.
Avalanche Summary
Avalanche control in Yoho, Kootenay and Sunshine produced mixed results. Most produced sluffing, or wind slabs to size 2.5. There were 2 examples of avalanches stepping to near ground layers, both on high/smooth alpine terrain where facets are likely more prominent. Lake Louise ski hill also used many explosives and had minimal results.
Confidence
Due to the number of field observations on Thursday
Problems
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.