Northwest Inland

The snow load on a layer of buried surface hoar may be reaching threshold for surprisingly large avalanches, especially at tree-line.

Low - Due to the number of field observations

Wednesday: Expect another 5-10cm of snow with freezing levels in valley bottoms and moderate southwesterly ridgetop wind. Thursday: 2-5cm of snow, freezing level in valley bottoms and  moderate southeasterly ridgetop wind. Friday: Mainly cloudy with sunny periods and light flurries, freezing level in valley bottoms and moderate southwesterly ridgetop wind.

It sounds like there were touchy conditions out there over the weekend. Reports of some large skier triggered and skier controlled avalanches from tree-line suggest that the load on the recently buried surface hoar is reaching critical levels.

Fresh storm and wind slabs are bonding poorly to a variety of old snow surfaces including a crust at lower elevations and south facing slopes, and/or facets and surface hoar on cooler shaded slopes. The most critical of these is the buried surface hoar, which has the potential for remote triggering, wide propagations and prolonged sensitivity to triggers. It is likely lurking on cooler shaded slopes. Recent snowpack tests gave easy to moderate results within the recent storm snow on a treeline slope. Check out the Mountain Information Network for more information.