Regions
Banff Yoho Kootenay.
Additional load with a cold NE storm Sunday will keep the danger HIGH. Cold temperatures after the storm should tighten up the lower elevation instabilities. Avalanche Control on Sunshine Road and Mt. Whymper tomorrow! JBW
Weather Forecast
A cold upper trough will cut off the strong southwesterly sub tropical flow creating a winter north east storm overnight and into Sunday. The skies will clear and the temperatures drop in the wake of the cold front.
Snowpack Summary
Up to 50 cm of storm snow has created a new snow slab which is failing easily on the old snow surfaces in the alpine. At treeline and below, rising freezing levels and rain have created a moist to wet slab condition.
Avalanche Summary
Natural avalanches are running on all aspects and elevations up to size 3.5. Storm slabs from the upper start zones are pulling out additional moist slabs and wet avalanches in the lower tracks. Steep slopes in the valley bottoms are failing as wet loose avalanches.
Confidence
Intensity of incoming weather systems is uncertain
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.