Avalanche Forecast

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Highest snowfall amounts are forecast for the south of the region in the mountains near Williams Lake, Clearwater and Blue River.

Saturday night: Snowfall 3-8 cm, moderate to strong SW wind, treeline high around -7 °C.

Sunday: Snowfall 10-20 cm in the south, 5-10 cm in the north, moderate SW wind, treeline high around -5 °C.

Monday: Snowfall 5-15 cm overnight then isolated flurries, moderate NW wind, treeline high around -8 °C.

Tuesday: Mainly sunny, moderate NW wind, treeline high around -15 °C.

The theme over the past week has been large cornice failures and wind slab avalanches size 2-3 in the alpine. Last Sunday, a snowmobiler accidentally triggered a large wind slab (size 2.5) on a lee alpine slope. The fracture line was up to 1 m deep.

A deep persistent avalanche problem in the North Columbia forecast region has produced large and notable avalanches during periods of changing weather. And the southeast corner of the Cariboos appears to have a similar lingering problem. Last weekend, explosives triggered a 2.5 deep persistent avalanche on a NE aspect at 2100 m south of Valemount.

15-30 cm of new snow is forecast to fall by the end of the day in the south of the region, 10-15 cm in the north. The new snow falls over faceting wind affected surfaces in the alpine, a melt-freeze crust on steep solar aspects & low elevations and a widespread layer of large surface hoar crystals. New snow is expected to adhere poorly at this interface.

There are three prominent layers in the upper snowpack which have been largely dormant during the dry spell but may become reactive with new snow loads. These include a thin crust and a spotty layer of surface hoar down 20 cm, a layer of facets and small surface hoar around 60 cm deep, and a thick layer of facets from the end of December 80-100 cm deep.

The lower snowpack is strong and settled in most parts of the region, except the southernmost part of the region around Blue River where there is a deeply buried crust/facet layer from early December that could be exhibiting similar behavior to the deep persistent slab problem in the neighboring North Columbia region. This layer is most prevalent at below treeline elevations and has been reactive to heavy triggers like smaller slab avalanches that step down. Check out our latest forecaster blog on the crust that never dies.

• Storm slab size and sensitivity to triggering will likely increase through the day.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.
• Dial back your terrain choices if you are seeing more than 20 cm of new snow.
• Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
• The trees are not a safe haven right now.
• Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.