Warmer temperatures and moderate winds over the past couple days have turned the snow near the surface into a cohesive slab. This is a problem because under that slab of snow is a very prominent buried weak layer (surface hoar). We’ve received many reports of 12-15’’ soft slab avalanches occurring over the past 48 hours. Currently, the most likely place to trigger an avalanche is on slopes above 30 degrees near treeline on all aspects. The surface hoar is preserved and problematic in sheltered areas. Also, leeward slopes near ridgelines are a concern. The wind transported snow is being formed into new wind slabs. Have extra caution on slopes with freshly wind deposited snow (E-NE-N). Stiff wind slabs can store the energy need to produce large avalanches. Sometimes they’re just waiting for a trigger…don’t be the trigger today!
The buried surface hoar layer is wide spread and problematic. Now that the snow near the surface has turned into a slab, expect to see more avalanche activity on the buried surface hoar layer. The buried surface hoar has been easy to find. It lives about 2-3 inches above the stout rain crust about 10-20'' below the surface.
Surface hoar before it was buried
Snow has been on the move! The soft loose snow on the surface has been blown and re distributed by mother nature. The recent winds have been out of the SW so I anticipate most wind slab problems occuring on E-NE-N slopes but be heads up for cross loaded slopes. Any leeward slopes above treeline, steeper than 30 degrees, should be avoided.
Snow and wind will increase today. Winds will continue to be out of the SW at a moderate 12-15 mph. Detailed weather forecast show 3-5'' of snow accumulations today. The next chance of signifigant accumulation will be on Thursday. Current forecast show up to 10'' of snow Thursday night. The more snow we get this week the more the avalanche danger will trend up. Now is a good time to make conservative choices while snowmobiling and skiing in the backcountry.
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