Wind slabs may be reactive, especially during periods of warming and direct sun
Verify conditions as you travel and back off if you notice signs of instability.
Wind slabs have formed on leeward slopes at upper elevations. The most likely areas for triggering will be steep and convex leeward slopes at upper elevations, or where recent snow covers surface hoar.
Use extra caution in areas with a thin snowpack of less than 100 cm. These areas are inherently weak, with faceted snow and crusts closer to the surface, making them easier to trigger.
On Wednesday, a size 1 wind slab was accidentally triggeredby a skier on a northwest-facing treeline slope. A size 2 naturally triggered wind slab occurred on the same aspect, but in the alpine.
Looking forward: We expect wind slabs to remain triggerable, especially during periods of warming and in areas where they overlie surface hoar.
Up to 30 cm of recently accumulated storm snow covers a variety of old surfaces, including surface hoar in wind-sheltered terrain, and a sun crust on steep south-facing slopes. Warming temperatures and sun tomorrow may make wind slabs more reactive.
In the mid-snowpack, a melt-freeze crust exists that was buried in mid-December. This layer is most prevalent at treeline elevations and below.
The lower snowpack consists of a thick melt-freeze crust, with weak faceted snow and/or depth hoar near the ground.
Snow depths vary widely across the region, averaging roughly 100 to 200 cm at treeline.
Friday Night
Cloudy. 30 km/h west ridgetop wind. Treeline temperature -7 °C.
Saturday
Mostly sunny. 35 km/h west ridgetop wind. Treeline temperature -1 °C. Possible temperature inversion forming. Freezing level rising to 1700 m.
Sunday
Mix of sun and clouds. 0 to 2 cm of snow overnight. 30 km/h west ridgetop wind. Treeline temperature -3 °C.
Monday
Mostly cloudy. 0 to 2 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level rising to 2000 m.
More details can be found in the Mountain Weather Forecast.
