Avalanche Forecast

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Saturday night: Decreasing cloud, isolated flurries with trace accumulations, light west wind, alpine temperature -8 C.

Sunday: Mostly cloudy, convective flurries with up to 5 cm of snow, higher accumulations possible in the south of the region, light west winds, alpine high temperature -4 C, freezing level 800 m.

Monday: Mostly clear, light southwest winds, alpine high temperature -3 C, freezing level 1100 m.

Tuesday: Increasing cloud, 5-10 cm of snow, moderate southwest winds, alpine high temperature -3 C, freezing level 1200 m.

Consistent reports of avalanches releasing on the February 22 surface hoar have been submitted over the past week. Human-triggered and remotely-triggered avalanches have been reported by nearly every operation region-wide, even as professionals tiptoe around and avoid suspect terrain features. The problem is touchy but tricky. In many instances, slopes were ski cut with no results, only to have the third or fourth skier in the group trigger the slab. Avalanche size has increased over the past week, with more of the activity releasing size 2+. Observations extend to all aspects and elevations, but north to east aspects near treeline have been a hot-spot for reactivity. 

Avalanches are also occurring at unusually high elevations for surface hoar, with several cases of wind and storm slabs stepping down in the alpine. Shallow avalanches in the most recent storm snow have the potential to step-down this deeper layer. Use added caution on sun-exposed slopes when the sun is shining, as it could rapidly deteriorate the storm snow and cornices and cause loose or slab avalanches.

Snowfall amounts varied across the region on Saturday, with the highest totals falling in the southern part of the region. Areas that accumulated more than 20 cm may have formed a storm slab problem prone to human triggering. In areas where less snow accumulated, slab formation will likely be specific to where the wind has transported the snow into deeper drifts. 

A widespread weak layer of surface hoar is buried 50-90 cm deep. On solar aspects, this layer may sit over a crust. Incremental loading from successive storms, strong winds, and mild temperatures have increased the depth and slab properties of the snow above the weak layer, increasing the potential for larger avalanches with more serious consequences. Riders will be capable of triggering this layer for some time until there is a substantial change in the snowpack. Read more about surface hoar on our forecaster blog.

• Be aware of the potential for large avalanches due to the presence of buried surface hoar.
• Use conservative route selection and resist venturing out into complex terrain.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.
• Even brief periods of direct sun could produce natural avalanches.