Strong winds over the last 48 hours combined with some wet snow and rain have created some dense new windslabs throughout the local mountains. Some of these slabs will have formed on a slick rain crust from last weekend's rain event which will increase the hazard and likelihood of triggering the slab.In shaded terrain, there was also a layer of unconsolidated dry snow above the crust which will help to lubricate the crust/ windslab interface. Tamarack Ski Patrol reported fast moving windslabs riding over this layer of unconsolidated snow above the crust and going further downhill than expected during their snow safety work yesterday morning. Steep leeward, windloaded slopes should be avoided or only approached after careful snowpack assessment. Crossloading will likely have occurred as well on East and West aspects as the winds were predominantly out of the South. Winds will be calmer today but increasing tonight. Expect the windslab problem to continue to increase as the slabs get thicker and more dense from warm snow and the possibility of rain in the upper elevations again today. Cracking, hollow snow, drummy sounds, a sculpted snow surface, thick pillows, and scoured areas are all clues that should help you recognize wind slab problems.
The rain line rose last weekend to above 7,000 feet and then refroze into a stout crust on most aspects. 4-6 inches of mostly dry new snow fell on that crust. Over the last 2 days we have picked up a couple of additional inches of Grauple and wet snow topped with another round of rain yesterday. The added stress of rain and above freezing temperatures will increase the possibility of loose/wet avalanches on slopes over 35 degrees today. Brundage Mountain Cat Ski guides reported a decent sized loose/wet slide that they were able to ski cut on a West facing convexity. As the new snow continues to pile up on the old crust, wet storm slabs will likely form adding to the avalanche problem. Know what you are riding on, take the time to check the snowpack before committing to any steep slope today.
This photo is of a skier triggered loose/wet avalanche near Tamarack Resort that occurred on Tuesday.
Pit Photo from 3/9 in the 20 Mile Drainage at 8000 feet showing last weekend's rain crust (just above the shovel handle) with about 6 inches of new, dry snow above. Below the crust layer there are some density changes but overall a strong, well consolidated snowpack.
Here is an update published by the Wallowa Avalanche Center with additional information on the tragic death of avalanche forecaster Kip Rand. http://www.wallowaavalanchecenter.org/kip-rand
The West Central Mountains got another round of high elevation rain yesterday. Local Snotel stations reported between .5 and .75 inches of snow water equivelant yesterday and last night. Temperatures this morning are hovering just above freezing at 6500-6800 feet. Expect wet, sticky snow above 7000 feet and melted snowcones in the lower elevations today. Tomorrow we will see a cool down and the good news is that winter will return Sunday and Monday with significant snowfall forecasted for the West Central Mountains and most of the Western US. Temperatures early next week are expected to remain below average!
Today's warm wet storm will be followed up with a cold front that will bring snowlines down tonight, tomorrow is going to be another unseasonably(unreasonably) warm day followed by a significant cool down and some serious moisture. If things line up the way the NWS and weather models are predicting, get ready for a powder day Sunday and a deep one on Monday. Cool temps will stick around through mid week.
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.