The winds howled during the last storm that caused widespread natural avalanches early Thursday morning. Be on the look out for wind slabs in likely and unlikely places (below cliffs, cross-loaded slopes). These new wind slabs are going to be reactive on all leeward (downwind) aspects over 30 degrees that have obvious signs of wind loading (smooth rounded pillow like snow surface) and could range from 6 inches to 3 feet in depth. These wind slabs could be located mid-slope on steep open faces. This will allow you to get half way down a slope before getting into trouble.
Surface Hoar, and Near Surface Facets that formed during our last extended cool, dry weather are now buried about 33CM/ 1 foot down. Natural avalanches went Thursday morning on many wind loaded Northern, Eastern, and South Eastern slopes...this persistent weak layer has the potential to linger for a while in our snowpack, and is a very common factor in avalanche fatalaties...take the time to dig, and evaluate every slope above 30 degrees, and stay far from the bottom,or run-outof steep slopes!
This foot of new, dry, cold snow has the potential to run with you, or sluff. Pay attention to your sluff it can knock you off your feet, and put you into places you would rather not be.
It is game on for avalanche conditions in the backcountry! Slopes over 30 degrees warrent respect and patience. With 12 inches of new snow and the perfect making of an avalanche (surface hoar/facets with a new slab on top) these are prime condintions to get into trouble if you do not carefully evaluate the snowpack and make conservative decisions. Keep to lower angle slopes in sheltered terrain today and enjoy the cold powder.
Yesterday, we toured the Rapid Creek area East of Jug Mountain and found evidence of Natural avalanches large enough to bury or kill a person on a couple of SE aspects, and more buried surface hoar 45 cm down, in our pits that scored moderately in tests, and a crust combo on a SE aspect.
Thursday we toured a large chunk of the advisory area, and we were not suprised to find fresh evidence of natural avalanches on mainly Northern aspects that went on a layer of buried surface hoar (33CM Down) that formed during our cool dry spell. The winds overloaded this layer, and it is still buried, waiting for a trigger in many other places. More snow will ramp up the danger on this persistant weak layer. We had simiar reports from Tamarack, but also on South aspects there.
Snow showers will be the theme of the day with 3-5 inches forecasted for the higher elevations, and 1-3 inches forecasted for McCall. Winds will be out of the West/Southwest around 17 MPH up high, and around 6 MPH this afternoon in McCall.
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.