Wind is the critical factor and reactive wind slabs on a variety of aspects may be lurking.
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
Arctic air continues to be entrenched in the Lizard and Flathead region. The pattern will start to shift Thursday to a zonal flow, allowing Pacific frontal systems to make way into the Interior early next week. Little change is expected for the weekend.Thursday/ Friday/ Saturday: Cloudy with sunny periods accompanied by a slight alpine inversion and warmer temperatures by Sunday. Alpine temperatures near -15 and valley bottoms -20. Ridgetop winds light-moderate from the West.
Avalanche Summary
A round of natural loose dry and storm slab avalanches up to size 1.5 were reported on Tuesday. Additionally, explosives triggered one size 1.5 storm slab on a northeast aspects at 2100 m elevation which was 15-20 cm thick. On Thursday, recently formed wind slabs may still be reactive to human triggering. With the winds recently switching directions, wind slabs should be expected on a variety of aspects.
Snowpack Summary
15-20 cm of recent snow has buried a variable snow surface which consists of wind scoured surfaces, old wind slabs in exposed terrain, surface hoar up to 20 mm in sheltered terrain, and/or widespread faceted old snow. Recent moderate winds from all directions is has redistributed some of this new snow on leeward slopes and behind terrain featu. Deeper in the snowpack, the mid-December persistent weak facet layer has been more prominent and reactive in the Corbin area than areas closer to Fernie. The layer is generally considered dormant right now but may wake up during the next storm or period of warming.
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.