Loose, wet avalanches occur when water is running through the snow pack. Our chances of loose, wet slides are dwindling, but with a lack of freezing temperatures over the last few days in the upper elevations due to the latest inversion, we will have to wait a bit longer to let our snow pack set-up. We have just had a brief freeze late last night that should help stabilize the snow surface, but temperatures are forecasted to rise again this evening.
Persistent Slab avalanches can be triggered days to weeks after the last storm.They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.
Triggering a slab due to this weak layer is becoming more difficult, but I would not let my guard down, especially during times of warm ups where water is running in the snowpack. Take the time to carefully assess terrain choices on the north half of the compass today. Especially areas where the snow cover is thinner which allows the buried surface hoar to be closer to the surface, and in turn more reactive---especially for snowmachines.
We have been tracking two persistent weak layers in the top three feet of our snow pack. One is buried deeply and was blanketed by the MLK storm cycle, the other near the surface. The warm temps and direct sun light is making the layer closer to the surface hard to find. The deeper buried layer is not as easily affected by sun and warm temps and remains intact on north facing slopes that are protected from direct solar radiation. We are tracking this weak layer, and are finding it better preserved/ more reactive in some places than others. This is the same layer that is the cause of the fatal avalanche on January 31st. A persistent weak layer such as this is a low probably, but HIGH CONSEQUENCE scenario.
The Friends of the Payette Avalanche Center (FPAC) is vital to the operation of the Payette Avalanche Center, and they need your support!
This Saturday evening at the Little Ski Hill from 6-9 PM. Some of the goods: Beer from McCall's own SRB, Waverunner rental from Cheap Thrills, Jug Mountain Ranch Mountain Bike Shuttles and skis from Dynafit! Practice up with those beacons and get ready for some timed beacon races with great prizes. Family Friendly environment with night skiing, BBQ and plenty of parking available on both sides of the highway. Thanks to all the donors that have supported us in the past and again this year! Kids are FREE at the door (does not include night skiing).
Thursday, we toured out to Box lake in a snowpack that felt more like water. Creeks are open and flowing strong. The upper 4 inches of the snowpack was saturated from the continued warm, inverted temperatures. Even Northern slopes had some rollerballs peeling off the ridges...putting debris on all aspects. South and West slopes had a fair amount of loose, wet debris from slides over the last few days. We were able to find our persistent slab problem weak (buried surface hoar) layer about 80cm down, but could not get it to fail in our stability tests.
Light snow this morning won't add up to more than an inch. Temperatures in the mountains will be a bit cooler, around 33 degrees, than in the valley as the inversion has moved out. Winds will be outof the West around 15MPH. Tonight, temperatures should rise a little: around 32 by 4AM, but increase chances of precipitation bringing in around 1-3 inches of snow with a Southwest wind 10-14 MPH.
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.