The rain line rose Sunday to around 7,000 feet. The new snow (4-6") is resting on a crust (below that crust, below 7,500 ft the snow is still damp) that formed from either rain or very wet snow hitting the surface of the snow. Northern slopes that have large overhanging cornices will likely be tender...give these giants some room, and stay far back from the often hard to determine edge. This was the first time that layers in the snow pack got saturation from the rain, and they are still damp from the rain.
It may take a while for the damp snow that lies beneath the crust to re-freeze...Careful snow pack evaluation, cautious route finding, and conservative decision making are essential as the Sun heats up the snow surface today---natural avalanches are likely and human triggered avalanches are possible! If you see signs of an overheating snow pack, like roller balls, point releases, which usually start near rocky outcrops, or a sinking into the snow above your boot tops, move to a cooler aspect.
Winds out of the South/ Southwest drove the last round of snow, sometimes reaching speeds of 41 mph. Expect to see some new, shallow wind slabs near ridge tops leading into NW, N. NE, and East aspects. The wind slabs should stabilize quickly as temperatures in the last 24 hours have trended downward, and are forecasted to do so over the next 24 hours. Cracking, hollow or drummy sounds, sculpting of the snow surface, thick pillows, and thin spots are all clues that should help you recognize wind slab problems.
Yesterday, we toured out to the Fisher creeck drainage...we saw some old, and new point releases in the new 4-6" of snow that is resting on a crust that is about an inch or two thick, and slicker in places than others...the sun came out a few times, and started some of these point releases. We were able to get some shallow fresh wind slabs to release under the weight of a skier, but they were loacalized, and did not move much at all. We noticed a much more winter like snowpack above 7500 feet.
Today, the Sun may make an appearance before clouds increase in the wake of another storm moving in. High temperatures will reach around 33 degrees around 7600 feet, and 37 degrees around 5,000 feet in McCall. Winds will be out of the Southwest around 5-10 mph. Tonight 1-3 inches of new snow should fall in the upper elevations, but McCall will only see a trace.
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.