Last week's storm left us with wind slabs on a variety of aspects, some of these slabs are resting on a weak layer of snow above a well preserved crust. This layer has produced human triggered avalanches in the last week. While these slabs are not widespread, their ability to propagate and the unpredictable nature of their distribution should cause you to approach steep, exposed terrain with caution today and through the next few days.
Yesterday we found a combination of wind slabs in wind loaded upper elevation terrain that were overlying soft unsupportable snow that consists mainly of graupel, or pellets. These slabs are most likely to be found on upper elevation North through East aspects today but be aware that other aspects could also be harboring pockets of wind slab on minor terrain features or where crossloading has occurred. Watch for visual clues of wind effect and manage your slope angles as you travel in wind affected terrain. These slabs should begin to bond as the temperatures increase over the next few days.
A layer of faceted snow exists above the February 4th crust and around a series of sun and melt freeze crusts in some areas. These layers have produced avalanches in windloaded areas over the last 2 weeks, and fresh eveidence yesterday on Council Mountain and the surroundiong ridgelines. The layer of concern is now buried just about 2-3 feet down in the snowpack and has shown the potential to propagate easily when triggered by a skier or rider which is what happened on the W/SW aspect of Sargent's Mt. that produced a good sized avalanche last Sunday. In some areas, this layer bonded to the new snow above and the crust has broken down or was very weak to begin with, in other areas. possibly more prevalent in the middle elevations 6500-7500 feet, the crust and facet combo persists and should be taken very seriously. The distribution of the layer is erratic and the only 2 ways you are going to insure your safety are by either digging in and finding out if this layer is present where you are riding or skiing or by avoiding slopes over 35 degrees. You can also help minimize your risk by using good travel protocols and avoiding steep, rocky areas where the snowpack is less uniform and you are more likely to find a shallow trigger point.
Conditions are variable across the forecast area right now. Our advisory is based upon a small number of observations. Please let us know what you are seeing out there whether it is deep stable snow or avalanche activity. Observations can be submitted here.
Yesterday we toured Council Mountain. Natural Avalanches had failed about 2 feet down on a graupel layer that produced moderate to hard results (ECTP25) in our pit tests. There was also a combination on the surface of wind slabs and graupel and surface hoar that were not bonded to eachother. This layer could produce big avalanches in the future as it is very well preserved right now, and within the depth that skiers and riders can effect.
|0600 temperature:||22 deg. F.|
|Max. temperature in the last 24 hours:||26 deg. F.|
|Average wind direction during the last 24 hours:||W|
|Average wind speed during the last 24 hours:||8 mph|
|Maximum wind gust in the last 24 hours:||24 mph|
|New snowfall in the last 24 hours:||NA inches|
|Total snow depth:||67 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.