The persistent slab problem is still on the radar, but shifting into a low-probability/ high-consequence situation. Be confident in your local snowpack before committing to any big terrain.
Summary
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Light snow starts on Friday night and continues through the weekend. (Estimates: 5-10 cm on Saturday; 1-5 cm on Sunday). Light flurries continue on Monday. The freezing level is around 1600 m by day, falling towards valley floor by night. Winds are generally light.
Avalanche Summary
Persistent slab, storm slab, and loose wet avalanche activity has tapered off recently. While the likelihood of triggering a large avalanche has gone down, the consequences remain high. On Wednesday, a naturally-triggered size 2.5 wind slab was observed on a NE aspect at 2500 m. An ice fall also triggered a size 3 deep persistent slab which failed at ground. Human-triggered wind slabs and persistent slabs are still a concern, especially on steep, unsupported slopes in the alpine. Stability is generally expected to improve with the cooling trend but this may take a few days at higher elevations.
Snowpack Summary
10-20 cm dry convective snow was shifted by NW winds into wind slabs on lee slopes in the alpine. These overlie a recently formed crust which varies in thickness with elevation. Below about 2000 m, loose moist snow makes up much of the snowpack underneath a surface crust. Several persistent weak layers exist in the upper metre of the snowpack which remain a concern. The mid-March crust/facet layer is down around 60 cm and has been reactive to light triggers recently. Down around 80 cm is the mid-February crust/facet/surface hoar layer which has also been reactive to heavy loads like avalanches in motion stepping down, cornice failures, or explosives.
pgoddard,
Avalanche Canada
