Kootenay Boundary

Persistent slabs sitting on a weak layer of surface hoar remain likely to human trigger.

Strong west winds may form reactive wind slabs in open terrain.

Moderate

• We are uncertain about how quickly persistent slabs are gaining strength.

On Saturday, a rider triggered a large (size 2.5) persistent slab avalanche near Whitewater. It occurred on a northeast aspect at treeline. See MIN for details.

Numerous rider triggered, large persistent slabs have been reported on all aspects and elevations over the past few days.

Up to 20 cm of recent snow accompanied by strong southwest wind has formed deeper deposits on north and east aspects. In sheltered terrain it will overlie a layer of surface hoar or a sun crust. The snow surface is expected to become moist on sun exposed slopes.

Several concerning weak layers exist in the upper snowpack:

• Mid February surface hoar and sun crust buried 15 to 40 cm deep.

• February 7th surface hoar and crust buried 25 to 45 cm deep.

• January 26th surface hoar, crust, and facet layer buried 50 to 80 cm deep.

The mid and lower snowpack are well settled.

Tuesday Night
Partly cloudy. 30 km/h west ridgetop wind. Treeline temperature -7 °C.

Wednesday
Mostly cloudy. 40 km/h west ridgetop wind. Treeline temperature -8 °C.

Thursday
Cloudy. 3 to 10 cm of snow. 50 km/h southwest ridgetop wind. Treeline temperature -6 °C.

Friday
Mostly cloudy. 3 to 10 cm of snow. 50 km/h west ridgetop wind. Treeline temperature -5 °C.

More details can be found in the Mountain Weather Forecast.

• Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
• Strong wind is building wind slabs farther downslope than usual.
• Be aware of the potential for remote triggering and large avalanches due to buried surface hoar.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks, or recent avalanches.
• In times of uncertainty, conservative terrain choices are our best defense.