The new snow interface will begin to strengthen over the next few days but the presence of a significant grauple layer in some areas will continue to be a problem as the overlying slab gains strength. This layer was widespread throughout the Tamarack Out of Bounds Terrain yesterday and found at the bottom of the new storm slab between 10 and 16 inches down in areas over 7000 feet.
Northerly slopes have seen a fair amount of loading over the last week beginning with the light density snow at the beginning of the week and during the last storm. Leeward slopes have significantly more snow than the surrounding aspects right now. Some of these windloaded area are also harboring persistent weak layers that were formed from early season storms on sheltered/shaded terrain.
We toured north of Tamarack Resort yesterday and found a rapidly changing snowpack. Dense, warm, wind impacted new snow left a slightly upside down snowpack that may provide some sporty crust skiing today. We experienced a large collapse(whumpf) on a low angle slope near the starting zone of Wildwood Bowl. We found snow depths ranging from 48-64 inches depending on the amount of wind loading and elevation in the upper portion of that area. Our test results showed a weak layer of newly deposited grauple near the beginning of the storm cycle. Compression Tests and Extended Column Test failed repeatedly on this layer which was about 15 inches down. Hasty pits and mit pits showed the weak layer to be widespread. Our test scores showed a variety of low to moderate scores with clean, planar but resistant shears. Near the ground we found rounding depth hoar that also failed in a deep tap test. The most notable observation is that right now we have a variable snowpack depending on location with different problems lingering from the October/November storms and newly deposited wind and storm instabilities. The only way you are going to know what's happening where you are recreating is to dig in and find out. As we collect baseline info about the snowpack in a variety of areas, your observations are invaluable to painting the bigger West Central snowpack picture. You can submit observations through our site or by emailing us at firstname.lastname@example.org.
Expect to see snow showers tapering off today with an approaching Arctic air mass accompanied by increasing North winds expected to be in the 18-23 mph range by mid day. The temperature will fall throughout the day bringing the coldest temperatures of the season thus far. Wind chills will be in the -8 to -18 range with an overnight low near -19 in the valleys. Single digit highs with wind chills are going to make it feel even colder through the weekend.
This avalanche advisory is provided through a partnership between the Payette National Forest and the Payette Avalanche Center. This advisory covers the West Central Mountains between Hard Butte on the north and Council Mountain on the south. This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires at midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.