There is about 18 inches of new snow resting on a crust, and for the most part well bonded. The snow has a tenancy to want sluff, or to run with you on steep slopes above 38 degrees. Many steep slopes, especially South, have already slufffed naturally. Use caution, and good sluff management while riding or skiing in exposed terrain where you may get knocked off course, and into the many obstacles that have yet to be buried like rocks and trees.
The storm on Thursday brought with it gusty winds that started from the Southeast and wrapped around the compass to the West during the day. Wind speeds at Granite Mt were recorded near 30 mph. The combination of a significant snowfall and wind will have created wind slabs on exposed upper elevation terrain. These slabs are going to likely be just below the ridgelines, but may form well down into the midslope....Pay attention to changes in the texture or look of the snow pack in areas that saw the direct effects of the winds and expect newly formed wind slabs on a variety of slopes today. Cracking, or sudden changes in how deep you are traveling in the snow pack are indicators of wind slabs.
More snow and significant winds are forecasted Sunday night, which will increase the wind slab avalanche problem for Monday.
We toured up to Hum Lake Saddle in the Lick creek drainage on Saturday, and did not see much natural activity other than sluffing, and minor wind slabs that had failed in the new snow during the storm. Cornices are growing, we observed a Glide crack below the rocks on a NE face above Hum lake. Our test pits (SW and NW) showed moderate failures in compression on the new snow interface, and no propagation in Extended column tests. The lower snowpack is still damp, and will hopefully freeze solid sooner than later? Coverage has improved greatly, but there still are many trees and rocks that need to be buried. We also noticed a sun crust that formed during the day on steep south slopes.
Thursdays storm laid down around 18 inches of snow that is resting on a thin crust that formed from the warmup. The upper 9 inches of new snow right now is very light density, the kind that snow lovers smile about. Our test results on the crust were moderate in compression, but lacked energy to propagate during an ECT. The rest of the snowpack seemed damp still, but on the path of freezing.
We observed natural wind slab avalanches on E,NE slopes Friday in the Grassy twins and Hazard Lakes area, and also got a report in the Titus lot from a local snowmobiler of a natural wind slab that had pulled out during the storm about 18 inches deep. Time will likely heal the wind slab problem, but stay alert in wind loaded terrain.
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.