Avalanche Forecast

Moderate - Due to the number of field observations

Sunday night: Cloudy with clear periods. Light northwest winds.Monday: A mix of sun and cloud, becoming cloudier over the day. Light southwest winds. Alpine high temperatures around -10.Tuesday: Cloudy with scattered flurries from the overnight period continuing and bringing 5-10 cm by end of day. Light southwest winds increasing in the evening. Alpine high temperatures reaching -3 or higher as an alpine above freezing layer establishes toward evening.Wednesday: Cloudy with increasingly wet flurries bringing 10-15 cm of new snow from the overnight period and over the day. Continuing but easing overnight. Strong southwest winds. Alpine high temperatures approaching 0 as freezing levels rise to 2000 metres by end of day.

Although we don't yet have reports of avalanche activity from Saturday in the Cariboos, observations from neighbouring regions show a spike in natural and human triggered storm slabs on a wide range of aspects and elevations. One of these was a large (size 2) snowmobile remote (from a distance) triggered storm slab in the Clemina Creek area, just adjacent to the Cariboos. Numerous other storm slabs were observed in the North Columbias and further south.Prior to the storm, a few large (size 2-3) natural persistent slab avalanches were reported last Sunday. These avalanches were reported on south aspects in the alpine. Last week numerous persistent slab avalanches (up to size 3) were reported on all aspects (a few that even destroyed mature trees). The persistent slabs were 50-150 cm thick and likely failed on the early December weak layer. Looking forward, expect a decrease natural avalanche activity while the potential for human triggering remains elevated. The existence of surface hoar beneath our new snow is likely to prolong unstable conditions.

Saturday's storm brought about 35-45 cm of new snow to the region. In many areas, the new snow will overlie a weak layer of surface hoar that was reportedly widespread at treeline and above in advance of the storm. This weak interface covers a few cm of storm snow from light snowfalls in days prior to the storm.Avalanche activity on the 110-180 cm deep weak layer that formed during the dry spell in early December has greatly diminished over the last week. This layer is composed of weak facets, surface hoar, and a sun crust on steep south-facing slopes. It is believed to be trending toward a dormant state after the loading test brought by Saturday's storm failed to produce reports of avalanches 'stepping down'. Places that might still challenge this assumption of dormancy would be steep north and east facing slopes between 1900-2300 m and steep south-facing slopes in the alpineA weak layer from mid-November and a crust that formed in late October are found near the bottom of the snowpack. The probability of triggering these deeper layers is low, but the most suspect areas would be shallow spots in steep, rocky terrain.