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RegisterDec 31st, 2018–Jan 1st, 2019
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Spooky and dangerous conditions exist where recent snow and wind have created thick slabs that sit over a layer of buried surface hoar. If venturing out into the mountains, beware of any steep, open slope. Careful navigation will be necessary for a safe day out.
On the 31st an observer in the Icicle Creek drainage found the snowpack to be very reactive. A supportable rain crust was found up to about 5,500ft. The snowpack above the crust at low elevations had begun to facet out, and surface hoar was observed growing on top. As soon as he got above 6,000ft, where the trees were more sparse, cracks began shooting out from his skis as he walked along the ridge. Avalanches were triggered from a distance while walking on this ridge. These were on average 18" deep, and easily up to 400ft wide. As the slabs slid downhill, light reflected off the shiny bedsurface, it was large, feathery, surface hoar. A widespread natural avalanche cycle had occurred during the tail end of the storm, but some slides may have released well after the snow stopped falling. We do not know much about the distribution of this layer across the ranges of the eastern slope. However, we need to treat our upper elevation terrain as guilty until proven innocent.
This past storm brought 1.8” of water equivalent at the Sasse Ridge Snotel site in the Salmon la Sac drainage (which could equate to nearly two feet of snow at higher elevations), while further east Mission Ridge picked up just an inch or two of new snow, but with winds of over 100mph. This is likely creating a pronounced difference in avalanche danger between the western and eastern portion of the ranges.
Coming soon.