The possibility of a large persistent slab avalanche means continuing to avoid large, steep, open slopes.
These avalanches may be hard to trigger, but the consequences would be serious.
Some natural wind slab activity was noted on Wednesday, and human triggering remains possible. There is also loose snow available for transport, so fresh, reactive wind slabs have the potential to form if the wind picks up.
A layer of weak, sugary snow surrounding a firm crust is buried 100 to 200 cm deep. Sun and warm temperatures were likely triggers for recent avalanches on this layer. Rocky alpine start zones would be a bad place for a human to be.
On Wednesday in the Seaton area, our field team saw numerous natural wind slab avalanches up to size 2 from earlier in the week. They also saw a large (size 2.5) naturally triggered persistent slab avalanche on a south facing slope at 1800 m. It ran across the normal trail, and likely occurred on the weekend. See their instagram post for a video.
This continues the trend of persistent slab avalanches around Smithers from late last week, including a remotely triggered size 3.
10-30 cm of recent snow is settling over a crust that is expected on the surface on all aspects at treeline and on all but north-facing terrain in the alpine. Above 1600 m, this crust is thin and breakable.
Generally southwest wind has formed wind slabs in leeward terrain.
A layer of weak, sugary snow over a thick crust is buried 100 to 200 cm and continues to produce large, surprising avalanches.
Thursday Night
Mostly cloudy. 30 km/h northwest ridgetop wind, decreasing to 20 km/h by the morning. Treeline temperature -4 °C.
Friday
Mix of sun and clouds. 20 km/h west ridgetop wind, decreasing to 10 km/h through the day. Treeline high 0 °C. Freezing level rising to 1500 m
Saturday
Mostly cloudy. 1 mm of precipitation as snow or rain at treeline. 20 km/h southwest ridgetop wind. Treeline high 3 °C. Freezing level rising to 1750 m.
Sunday
Mix of sun and clouds, potential clearing in the afternoon. 30 km/h southwest ridgetop wind. Treeline high 8 °C. Freezing level rising to 2300 m.
More details can be found in the Mountain Weather Forecast.
