Recently formed slabs continue to be sensitive to human triggering. Be diligent in your terrain selection.
Confidence
Fair - Intensity of incoming weather systems is uncertain
Weather Forecast
A well-organized pacific frontal system will likely arrive onshore tonight. Interior regions will start to see effects of this system by Thursday with cloudy skies and light precipitation 5-10 mm. Ridgetop winds will blow strong from the West and freezing levels will hover between 1600-2000 m. Friday and Saturday will bring continued precipitation with accumulations up to 20 mm. Ridgetop winds will blow moderate from the SW and freezing levels 1800-2100 m. On Sunday a ridge builds over the Interior, keeping things dry and clear, yet again….
Avalanche Summary
On Tuesday, several natural slab avalanches up to size 2 were reported from northerly-easterly aspects above 1800 m. Numerous explosive controlled slab avalanches were also initiated up to size 1.5 on easterly aspects above 2300 m. There is a still a concern for avalanches to step down to deeply buried weak layers resulting in larger slab avalanches, especially in shallower snowpack areas.
Snowpack Summary
At higher elevations, 10-30 cm of new snow sits over a plethora of old surfaces including wind affected surfaces, and/or old wind slabs and crusts which were buried mid-March. Previous strong winds have redistributed new snow into wind slabs on leeward terrain features and lower elevations (below 2000 m) are sporting spring-like, melt-freeze conditions. Digging deeper (20-50 cm below the surface) sits the mid-February facet/ crust interface. This interface has not been reactive in the Purcell's unlike regions to the North. However, its still alive and well in test profiles. It may just require additional load and/ or a change in slab properties before it reaches threshold and becomes reactive. The late-Jan crust/surface hoar layer (around 1m deep) and the mid-January surface hoar (around 1.5m deep) have been dormant for several weeks.
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.