Avalanche Forecast

SUNDAY NIGHT: Mostly cloudy, isolated flurries with a trace of snow, light south wind with moderate gusts at ridgetop, alpine temperatures around -15 C.

MONDAY: Mostly cloudy, isolated flurries with a trace of snow, light south wind, alpine temperatures around -12 C. 

TUESDAY: Cloudy, isolated flurries with a trace of snow, moderate southwest wind at ridgetop, alpine temperatures around -12 C.  

WEDNESDAY: Cloudy, isolated flurries with a trace of snow, moderate southwest wind at ridgetop, alpine temperatures around -12 C. 

On Thursday, a MIN report in the south of the region detailed a spike in wind speed and a shift in direction to northeast that formed touchy slabs, loaded cornices to their breaking point, and likely initiated a large avalanche in the alpine. A MIN report on Saturday indicated that a similar pattern of wind slab and cornice activity had previously occurred in areas around Valemount . 

Last weekend there was a very large (size 3) natural wind slab avalanche on a northeast aspect near Valemount, as well as this neighboring report of a very large (size 2.5-3) natural avalanche on a southeast aspect on Mt. Goslin. A few size 2 avalanches were also reported in the Barkerville area. These included a mix of wind slab and persistent slab avalanches on a 40 cm deep surface hoar layer, mostly on treeline features (see some photos in the MIN reports here, here, and here). One was thought to have been initiated by a machine-triggered cornice fall. Although the likelihood of triggering persistent slab avalanches is decreasing, this weak layer warrants assessment in open, sheltered slopes at treeline where this layer is likely pronounced and preserved.

Winds have varied in strength and direction over the past week, loading cornices and forming wind slabs at upper elevations that may still be possible to trigger. Watch for these wind slabs in unusual places as complicated cross-loading and reverse-loading patterns are prevalent. Wind slabs may overlie weak, sugary, faceted snow, meaning that they could break wider than expected and will likely be slow to bond. 

In wind-sheltered areas, the upper snowpack has become soft and faceted from the cold temperatures. 40-70 cm of snow from February is settling over a reactive weak layer of surface hoar buried in late January. Reactivity on this layer has primarily been observed at treeline and in "treeline-like" features, like cutblocks, that are below treeline. Snowpack test results continue to show instability on this layer, like this MIN report from Allan Creek on Friday. On steep south-facing terrain, this layer may consist of facets on a sun crust.  

Additional weak layers may present in the lower snowpack, but are not a concern in most areas until we see significant snow loading or rapid warming. 

• Recent wind has varied in direction so watch for wind slabs on all aspects.
• Approach lee and cross-loaded slopes with caution.
• Be aware of the potential for large avalanches due to the presence of buried surface hoar.
• Extra caution is needed around cornices under the current conditions.