Avalanche Forecast

Low - Intensity of incoming weather systems is uncertain

THURSDAY NIGHT: Snow, 10-20 cm around the Duffey and 25-30 cm near the Coquihalla. Moderate south wind with extreme gusts. Freezing level dropping overnight from 1500 m.FRIDAY: Heavy snow, 15-25 cm. Moderate to strong southwest wind with extreme gusts. Freezing level 1300 m.SATURDAY: Flurries, up to 5 cm snow. Moderate southwest. Freezing level 1300 m.SUNDAY: Flurries, 5-10 cm snow. Moderate southwest wind with strong gusts. Freezing level below 1000 m.

A layer of surface hoar buried just after Christmas has been reactive to skier traffic and snowpack tests through Wednesday. Last Sunday, several skier and snowmobile triggered avalanches were reported on this layer. There was a report of two skier triggered avalanches in the Zoa peak area near Coquihalla Summit. These were both reported to be up to size 2 and running on a layer of surface hoar buried 40-60 cm deep on a north aspect at treeline. See the MIN report here. An additional avalanche incident was reported by snowshoers in Manning Park. It is suspected to have run on the same weak layer. See the MIN report here.With heavy snowfall and high wind forecasted, humans may be still be able to trigger avalanches on this weak layer in southern parts of the region, and a more widespread storm slab problem will develop as new loading stresses the snowpack.

Heavy snowfall, rising freezing levels and extreme winds are setting up a widespread storm slab problem. Wind loaded terrain will be the first to develop reactive slabs.Approximately 20-50 cm of new snow starting Wednesday adds to 20-30 cm of recent snow that covers a widespread weak layer of feathery surface hoar that formed just after Christmas. This layer is reported to be most prevalent in the southern part of the region (e.g. Coquihalla Summit and Manning Park) at the upper end of treeline on north and east aspects. In the north part of the region, another weak layer composed of facets and/or surface hoar is buried 100 to 150 cm deep. This weak layer appears most prominent around treeline (up to 2000 m). There have not been reports of avalanche activity on this layer for the past week, but field observations suggest slab avalanches may still be possible on this layer where it exists.