Regions
Banff Yoho Kootenay.
This weekend's up slope storm has the potential to generate rapid storm loading conditions. Pay attention to cornices and monitor the interface of the new snow on the recently buried melt-freeze crusts at tree line and buried wind slabs in the alpine
Weather Forecast
Cool maritime air mass off the coast will produce a series of fronts, which for the Rockies will produce some significant snowfall beginning late morning on Saturday. This storm will be up slope in nature and will produce heavy snowfall at times. Winds will be light to moderate and freezing levels will be at around 1900 meters mid-day.
Snowpack Summary
2-5 cm of recent snow overlies a prominent rain crust from March 28th. The upper and mid pack is well settled and depth hoar is still evident as the basal characteristic in much of the forecast area, especially the east side of the continental divide. Wind slabs still linger on recently buried crusts on solar aspects will be the primary problem.
Avalanche Summary
Thin wind slabs with explosives produced up to size 1.0 in the alpine. No other avalanche activity reported or observed.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Saturday
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.