The rain line rose Sunday to above 7,000 feet. The new snow (4-6") is resting on a crust (below that crust, below 7,500 ft the snow is still mostly saturated) that formed last weekend. The added stress of heat and direct sunlight will increase the possibility of loose/wet avalanches on the Southerly terrain and on windloaded East aspects.. With the temperatures rising over the next few day, it will likely take awhile for the snow below the surface to refreeze. If you see signs of an overheating snow pack, like roller balls, point releases, which usually start near rocky outcrops, or are sinking into the snow above your boot tops, move to a cooler aspect.
Winds out of the South/ Southwest drove the last round of snow, sometimes reaching speeds of 41 mph. Expect to see some new, shallow wind slabs near ridge tops leading into NW, N. NE, and East aspects. The wind slabs should stabilize quickly as temperatures in the last 24 hours have trended downward, and are forecasted to do so over the next 24 hours. Cracking, hollow or drummy sounds, sculpting of the snow surface, thick pillows, and thin spots are all clues that should help you recognize wind slab problems. We found some of these wind slabs yesterday in NW terrain near the ridges where they were sitting above a layer of cold, unconsolidated snow that didn't get the soaking from last weekend's rain. We stomped around on them but could not get them to fail deeper than the shallow layer of new snow. We can expect a repeat of last week's storm over the next few days with increasing winds, and a warm front accompanied by a moist SW flow.
We toured around Boulder Mountain yesterday and found a rapidly warming snowpack on the E, S and SW aspects. We saw several decent sized point releases on steep East Facing slopes that were just beginning to heat up and lose cohesion. One of these entrained a decent amount of snow and left debris piles on trees below it. We also had a good sized point release or loose/wet slide reported by Brundage Cat Ski in Wong's Bowl yesterday. Most of these areas had just enough new snow (3-5 inches) on a slick crust that once the snow surface begins to warm up the unconsolidated snow is able to move pretty easily on top of the crust.
We also observed some cracking on protected northerly terrain where shallow wind slabs were left over from last weeks gusty winds. The rain crust from last week is evident on most aspects below the new snow and is providing a slick interface for the new snow and the isolated wind slabs. The sunny aspects developed a thin melt freeze crust yesterday as the clouds came back in later in the day. Great skiing and riding can be found in sun protected areas but use a little bit of caution and safe travel techniques as you search out the remaining powder stashes.
The West Central picked up about an inch of new snow overnight, today look for mostly cloudy skies with a chance of scattered snow showers throughout the afternoon. Temperatures will be rising tonight as a warm front and the first in a series of small storms enters the West Central. The front will also be accompanied by increasing S/SW winds with gusts to 46 overnight. Over the next few days we will see snowlines pushing back up towards 7000 feet with a few inches of snow each day for the rest of the week. The precipitation will be mostly rain in the valleys. The weekend will bring back freezing temperatures at night and a decrease in the chance of precipitation.
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.