New snowfall and strong winds are a sure recipe for a reactive Wind Slab problem. Variable snowfall amounts are forecast throughout the bulletin region overnight ; Alpine hazard may remain Moderate in the drier Marmot & Maligne regions.
Weather Forecast
A cold front tonight provides a burst of snowfall, followed by a cooling, clearing trend.Monday night: Snowfall, 5cm forecast (but upto 12cm in the Icefields area). Strong SW winds slowly easing. Treeline Low -11Tuesday: A few clouds (Broken cloud in the South). Winds ease to Light NW. Treeline High -8. Weds: Clear, cool, light winds.
Snowpack Summary
New snow accumulating over a variety of old surfaces (loose facets in sheltered terrain, wind affected in exposed areas, sun crust to treeline to solar aspects) . The mid pack is relatively strong for the region, supportive to skis in most areas. Isolated surface hoar is still reactive at/below tree line, South of the Icefields.
Avalanche Summary
No new avalanches observed Monday. On Sunday, A flight along the 93N observed a Size 2 cornice fall, not triggering any slab on the slopes below; and several small Loose Dry avalanches on steep, South facing alpine slopes. One large Whumph on flat treeline terrain South of the Icefields, on January 18 surface hoar, down 40cm.
Confidence
Forecast snowfall amounts are uncertain on Tuesday
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.