A persistent weak layer of faceted snow(2-3 ft from from the surface) can be found just above the hard Thanksgiving rain crust. This layer doesn't exist everywhere, but can be found in most mid to upper elevation areas above 7000 feet. Over the last few weeks, the snowpack above this layer has slowly consolidated into a significant slab. Pit tests show the potential for propagation at this layer and while failure is relatively hard to initiate, human triggered avalanches are possible especially where the snowpack is thin or where the overlying slab is weaker. The hazard may decrease after a couple days when the snowpack has a chance to solidly refreeze. This layer is fairly continuous throughout the Western U.S. right now and has already been responsible for several skier and snowmobiler burials in other parts of Idaho and nearby states. Check out this short video to see what the layer is doing in our test pits around the McCall area. In addition to this layer we are seeing weak snow layers around the many rocks that are exposed.
Isolated wind slabs are present near ridges and in exposed areas all across the forecast area right now. The wind slabs are shallow (around a foot) and have been reactive to ski cuts over the last week. We have also observed and had reports of natural avalanches on these isolated slabs over the last few days. They are unlikely to bury a person, but they may push you into obstacles, or worse, trigger the deeper persistent slab below. Common signs of wind slabs are drifted, textured and hollow feeling or sounding snow.
Yesterday afternoon, temperatures finally started to drop below freezing after 48 hours of above freezing temperatures all the way up to 7,000 feet. We observed a few wet slides on the road going up from Tamarack Falls yesterday. Stability from 5-7,000 feet should improve over the next couple of days thanks to the much needed freezing temperatures. Give it a while to heal. Yesterday, the snowpack below 7K was isothermal, and not inspiring confidence or trust.
Your observations very important to help us generate a larger picture of snow and avalanche conditions, please let us know what you are seeing while you are out riding or skiing in the local backcountry. It's super easy to send us info and photos with date, location, pictures, general or specific snow observations, just click on the submit observations page on the PAC website and add what you saw or found in the snow. You can also email the forecasters directly at: firstname.lastname@example.org
We observed a few wet slides on the road going up from Tamarack Falls yesterday. Our test pit on an NE aspect above Granite Creeck trail showed about 120cm/ 4feet of snow, and moderate results in compression, and no propigation on an ECT on the Thanksgiving Rain Crust persistent weak layer abot 30 cm/ 1foot down. The snowpack below 7K was isothermal/warm. Above 7K 3" of new snow on top a very thin rain/temperature crust softened up the surface to provide some good turns. Solar aspects were still very thin, and will benifit from some much needed snow.
|0600 temperature:||27 deg. F.|
|Max. temperature in the last 24 hours:||32 deg. F.|
|Average wind direction during the last 24 hours:||SW|
|Average wind speed during the last 24 hours:||10 mph|
|Maximum wind gust in the last 24 hours:||20 mph|
|New snowfall in the last 24 hours:||1 inches|
|Total snow depth:||59.68 inches|
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.