Northwest Inland

Fair - Due to limited field observations

Synopsis: The next storm system is tracking to the south along the US border so the region should see a period with cool temperatures, light westery wind, and little precipitation.Sunday: Generally light SW with moderate strength gusts. Mountain temperatures around -8 with below freezing at all elevations. Only trace amounts of snow in the forecast.Monday & Tuesday: Light wind from the SW or W. Even colder temperatures with highs around -15 in the mountains Tuesday. No significant snow forecast.

On Wednesday, a snowmobile triggered a hard wind slab at the Sinclair snowmobiling area. It failed on the November crust/facet layer 30 cm above the ground while side hilling. This deep crust/facet layer has been the failure plane for a number of large avalanches further to the west and was suspected to have failed at the Hankin-Evelyn area last weekend. Unfortunately, this weakness is unlikely to heal very quickly, so further deep avalanches are possible, especially as snow and wind-loading continue to stress the snowpack over the next few days.

Storm snow instabilities are likely to be slowly settling and gaining strength. Spotty surface hoar was buried in the upper snowpack, particularly in sheltered treeline areas. New and buried wind slabs are widespread and exist on a variety of alpine and exposed treeline slopes due to variable winds. Of key concern is a November facet/crust layer which can be found near the base of the snowpack. This layer, which is widespread, can be triggered from thin-spot trigger points, or with a heavy load, such as storm slabs stepping down, cornice fall or a snowmobile. It has the potential for very large, destructive avalanches and demands respect. A rain crust is buried in the upper snowpack at low elevations. In general the snowpack is highly variable in depth due to windy conditions this season.