Avalanche Forecast

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Wednesday night: Cloudy. Light SW wind. Treeline temperature around -12 °C. 

Thursday: Snowfall 10-15 cm in most areas, upwards of 20cm west of Castlegar. Moderate SW wind. Treeline high around -9 °C. 

Friday: Snowfall 20-40 cm in most areas, upwards of 50 cm at Kootenay Pass. Strong SW wind. Treeline high around -3 °C. 

Saturday: Mix of sun and cloud. Moderate SW wind. Treeline high around -6 °C. 

On Monday and Tuesday, storm slab avalanches were reactive naturally and to skier and explosive triggers, up to size 2. Recent snow appears to sit on a weak interface which may result in storm slab reactivity persisting longer than normal.

There has been an alarming pattern of large, persistent slab avalanches being consistently reported over the past week and a half. Almost all of these avalanches ran on the early December weak layer. Deeply buried persistent problems like these don't go away overnight, and it remains a serious concern. Additional loading by the weight of new snow will further stress this weakness and may result in a resurgence of reactivity.

• On Tuesday, explosive control work near Rossland produced a size 2.5 persistent slab avalanche on a layer of surface hoar from late December. 
• On Monday in the neighboring South Columbia region, a natural size 2.5 persistent slab avalanche was reported on a NE aspect at 2200 m failing 80 cm deep on the early December layer.
• A few notables from last week feature in our latest blog Photos of recent persistent slab avalanches in the southern interior. 

As the next storm rolls in, areas west of Castlegar can expect upwards of 20 cm of new snow to fall Thursday. The bulk of snowfall won't arrive in eastern areas until Friday but increasing winds can be expected to transport 40-70 cm of recent snow into reactive wind slabs in lee terrain features. The recent snow sits over variable and potentially weak snow surfaces including widespread facets, wind affected snow, and/or surface hoar up to 5 mm in sheltered areas. Reactivity at this interface may persist for longer than usual.

The early December crust/facet layer has been responsible for numerous very large persistent slab avalanches over the past week and a half. The depth of the crust ranges widely from 80-190 cm and has most recently been reactive in wind affected terrain near ridge crests. Nearly all of the recent avalanches on this layer have been triggered from shallow spots in the snowpack where the crust is less than 100 cm deep. Avoid steep, rocky slopes with a shallow or thin-to-thick transitions in the snowpack.

• Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
• Dial back your terrain choices if you are seeing more than 25cm of new snow.
• Be aware of the potential for large avalanches due to the presence of a persistent slab.
• Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
• It's critical to stay disciplined and choose only well supported, low consequence lines.