Watch for newly formed reactive wind slabs as you transition into wind-affected terrain.
Seek out sheltered terrain to avoid wind slabs and find the best riding.
Overnight snowfall and southwest winds have built fresh wind slabs in treeline and alpine lees. Expect to find wind slabs in exposed areas that are also below the treeline.
Wind slabs may be sitting on a crust making them especially reactive to ridder triggering.
Two weak layers consisting of a crust with small facets found above them have been reactive to rider traffic in the last week. The first, down 40-100 cm has been reactive at treeline in the Rhododendron and Pemberton Icefields area. The second is found down 60-150 cm and up to 1900 m. Both of these layers seem like isolated problems at the moment but if triggered they will result in large consequential avalanches.
On Saturday, wind-affected snow was reported to be reactive to skier traffic. A size 2 wind slab avalanche was released on a west aspect at 1700 m as a skier passed over a convex roll. See MIN for photos of the slide. A skier accidental size 1.5 storm slab avalanche was reported on a steep, northeast, treeline feature.
Evidence of several size 3 natural slab avalanches were observed. It is believed these avalanches ran within the storm and were 24 to 40 hours old.
On Friday, local operators were able to trigger a number of storm slab avalanches with explosives. Control work focused on mitigating the overhead hazards that cornices now pose. Make sure to use caution in areas where cornices are present.
By Monday morning 20 cm of new snow will overlie the previously 40-70 cm of recent wind-affected storm snow. As you descend in elevation wind effect decreases and the temperature effect increases and the new snow may overlie a crust.
A series of crusts are found at varying depths throughout the region. A crust from late January is found at all elevations down 40-100 cm with small facets above it. In the Rhododendron and Pemberton Icefield area, this crust has been reactive to skier traffic and in test pits at treeline. In the Brandywine area, a crust found 60-150 cm deep resulted in a handful of surprisingly large rider-triggered avalanches in the past few days. This layer exists to 1900 m.
Total snowpack depths are reaching 300 cm in some areas.
Sunday Night
Cloudy and snowing, 20-25 cm accumulation. Strong southwest winds easing to 20 km/h by morning. Treeline temperature -3 °C. Freezing levels 1000 m.
Monday
Mostly cloudy, 5-8 cm accumulation. West winds 20 km/h gusting 40 km/h. Treeline temperature -5 °C. Freezing level 800 m.
Overnight cloudy with isolated flurries, 2-5 cm accumulation. Freezing levels drop to valley bottom.
Tuesday
Sunny. Winds north northwest 10 to 15 km/h. Treeline temperature -10 °C. Freezing level 800 m.
Wednesday
Sunny. Winds west 10 to 25 km/h. Treeline temperature -8 °C. Freezing level 500 m.
More details can be found in the Mountain Weather Forecast.
