Avalanche Forecast

Brrrrrr! Cold and dry conditions persist under arctic air

Wednesday: Mostly clear, light northeast ridgetop wind, alpine temperature -25 C.

Thursday: Mainly sunny, light northeast ridgetop wind, alpine high temperature -27 C.

Friday: Sunny, light easterly ridgetop wind, alpine high temperature -23 C.

Saturday: Increasing cloud, light to moderate southeast wind, alpine high temperature -18 C. 

Over the past couple days, there have been two reports of very large avalanches (size 2.5-3) on southeast aspects in the alpine. These avalanches were thought to have released naturally, possibly due to the influence of solar radiation and a cornice trigger, and likely occurred over the weekend.

Over the last few days, small (size 1-1.5) loose dry avalanches in unconsolidated snow were reported in steep terrain. 

On Sunday and Monday, there were also reports of small (size 1) explosive-triggered avalanches breaking on a weak layer of surface hoar. Last week, a skier remotely triggered a size 2.5 persistent slab avalanche from a ridgetop near Quartz Creek, which also failed on the surface hoar. 

Up to 15 cm of low density snow over the weekend combined with previous strong northwest winds to create wind slabs which may be possible to human trigger in specific lee features. In sheltered areas, cohesion-less powder may be prone to dry loose avalanches that can run far and fast in these cold, dry conditions. With clear skies, there is uncertainty as to how much direct sun on Tuesday might warm steep slopes midday given the frigid temperatures.

50-80 cm of snow from the past week is settling over a weak layer of surface hoar. Recent avalanches on this layer have primarily been reported at treeline and "treeline-like" features below treeline in the northern half of the region. Although the likelihood of triggering these avalanches is decreasing, this weak layer warrants assessment in open, sheltered slopes at treeline where it is likely pronounced and preserved. 

Down 60-100 cm, an older layer surface hoar and/or a thin melt crust from mid January can be found. This layer was more prominent in the north of the region in sheltered, open slopes at treeline.

Deep persistent weak layers can still be found in the lower snowpack. These weak layers are most likely to be triggered from rocky areas with a shallow or thin to thick snowpack.

• Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
• Stay off recently wind loaded slopes until they have had a chance to stabilize.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
• Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.