Regions
Banff Yoho Kootenay.
An inversion is creating warm alpine temperatures even though it is cold in the valleys. This, combined with moderate to strong SW/W winds will raise the hazard on Thursday.
Weather Forecast
Thurs: Inversion with alpine temps in the 0 /-5 range. M-S SW/ W alpine winds. Clear skies.Fri: Inversion breaks down. Alpine temps -10/-15. M-S W/NW alpine winds. Overcast with possibility of 1-2cms.Sat: Alpine temps -5/-10. L-M SW alpine winds. Clear skies.
Snowpack Summary
Hard wind slabs exist in exposed alpine features but haven't been reactive to skier traffic. Suface hoar is growing in sheltered treeline locations. W of the divide, a well settled snowpack exists with the basal Nov 6 crust well bonded. In the front ranges E of the divide, a facetted snowpack exists with the Nov 6 basal crust being mainly facetted.
Avalanche Summary
No new avalanche activity.
Confidence
Wind speed and direction is uncertain on Friday
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.