A touchy persistent slab problem demands respect. Use extra caution in your terrain selection.
Confidence
Moderate - Timing of incoming weather systems is uncertain
Weather Forecast
Fairly benign weather is expected for the next couple of days ahead of the next storm due late Thursday. Overnight Monday: 5-10 cm snow; Tuesday/ Wednesday: flurries; Thursday: 10-20 cm. The freezing level drops from 1100 m to valley floor late on Tuesday. Moderate southerly winds become light by late Tuesday. For more details check out https://avalanche.ca/weather.
Avalanche Summary
Avalanche activity has been widespread over the last few days as recent snow has reached a critical load above a volatile weak layer. Human and naturally-triggered avalanches in the size 1-2.5 range have been most prevalent below treeline, but have also occurred at treeline and alpine elevations. Wind slabs have also been reported in wind-exposed terrain. A ski tourer was buried last week, and professionals continue to operate with great caution. Continued human triggering of persistent slab avalanches is likely.
Snowpack Summary
A 40-80 cm persistent slab overlies a variety of surfaces including large surface hoar, sun crusts, and facets. This slab is ripe for human triggers and is especially touchy below treeline. Recently formed wind slabs also exist on lee features at alpine and treeline elevations. The mid and lower snowpack are generally well settled and strong.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.