Avalanche hazard will increase throughout the day. Simplify terrain choices where more than 25 cm of new snow accumulates and seek out sheltered areas with soft loose snow.
20-30 cm of snow is forecast to accumulate by Wednesday afternoon. Gusting winds at ridge top and temperatures rising during the storm will speed up slab formation as new snow accumulates. Expect storm slabs to become increasingly reactive throughout the day. New snow and wind may bring cornices to their tipping point.
Tuesday night: Cloudy, 5-10 cm of snow, light southwest winds gusting at ridge-top, alpine temperature -12 C.
Wednesday: Cloudy, 10-20 cm of snow, higher accumulations forecast for the Monashees, moderate southwest winds gusting at ridge-top, alpine high temperature -8 C.
Thursday: Cloudy, isolated flurries, light southwest winds, alpine high temperature -6 C.
Friday: Cloudy, isolated flurries, light variable winds, alpine high temperature -7 C.
New snow, wind, and warming temperatures are expected to build a reactive storm slab problem prone to human-triggering where more than 25 cm accumulates. These conditions may also bring cornices to their breaking point.
During the weekend storm, numerous large (size 2-3) avalanches released naturally in the storm snow. These avalanches primarily occurred on leeward aspects at treeline and alpine elevations. A very large cornice fall was reported Sunday on a north aspect at 2400 m, and it stepped down to a large slab avalanche. Below tree line, large wet loose avalanches were releasing naturally on Friday and into Saturday.
With continuous stormy weather over the past week, there have been a handful of notable natural avalanches reported in the north of the region. These were very large (size 3-4) persistent slab avalanches breaking 100-250 cm deep on southeast, east, and northwest slopes above 2000 m. Although the likelihood is decreasing in the aftermath of the storm, touchy storm slab avalanches or large cornice fall may have the potential to step-down to this layer.
The forecast storm is expected to bring 30+ cm to favored areas such as the Monashees. Gusty winds are forecast for upper elevations as well as a gradual warming trend throughout the storm, which has the potential to speed up slab formation.
There have been substantial changes to the snowpack over the past few days. 40-80 cm of snow fell during the weekend storm above 1900 m, with the higher totals in the northeastern parts of the region. Extreme winds originating from the southwest and shifting to the northwest created a tricky loading pattern at treeline and above and increased concern for cornice triggers. During a warming event Saturday night, rain saturated snow surfaces up to around 1900 m that have since formed a crust.
The mid and lower snowpack is generally well settled and strong. In the north of the region, a weak layer of surface hoar buried 90 to 170 cm deep may persist in isolated areas.
