Carefully assess steep slopes for fresh wind slabs before committing.
If triggered, wind slabs could step down to deeper layers, resulting in very large avalanches.
Wind slabs are most reactive during their formation. Watch for active wind transport and avoid leeward areas with denser wind-bown snow.
Deep weak layers are most likely to be triggered at higher elevations, on wind loaded slopes.
Large, naturally triggered deep persistent slab avalanches have been observed recently on north-facing slopes. These failed on a weak layer 1-2 m deep, and some have stepped down to the ground. See photos below.
Check out this MIN from our field team.
5 to 10 cm of new snow accompanied by strong southerly wind is expected overnight Wednesday. This falls over 50 to 80 cm of wind affected, settling snow that is generally bonding well to the mid December crust.
A deep persistent weak layer consisting of a prominent crust, with 10 cm of facets on top, is buried 120 to 180 cm deep in terrain above 1800 m.
At lower elevations, the mid and lower snowpack is moist to the ground.
Wednesday Night
Cloudy. 4 to 10 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -1 °C. Freezing level 1200 m.
Thursday
Mostly cloudy. 30 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level 1600 m.
Friday
Mostly cloudy. 4 to 5 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level 1000 m.
Saturday
Mostly cloudy. 15 cm of snow. 20 km/h variable ridgetop wind. Treeline temperature -16 °C. Freezing level 0 m.
More details can be found in the Mountain Weather Forecast.
