THIS AVALANCHE ADVISORY EXPIRED ON February 24, 2016 @ 7:08 am
Avalanche Advisory published on February 23, 2016 @ 7:08 am
Issued by George Halcom - Payette Avalanche Center
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The avalanche danger will be MODERATE at upper, and middle elevations today. Avalanche danger will rise on solar aspects through the day as the Sun heats up the snow surface. Southeast winds pushed around a foot of new snow forming slabs at ridge-top towards the end of last week. It remains possible to trigger these soft or hard wind slabs in exposed terrain.  Below 6,000 feet the avalanche danger is LOW.

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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Winds out of the south, southeast and southwest hammered the West Central Mountains through the second half of last week. Wind gusts were in the 40-60 MPH range on the higher peaks and ridges with sustained winds in the 20+range. The avalanche danger on wind loaded upper elevation terrain is enough to merit conservative terrain choices on all wind affected slopes. These strong winds have done a great job loading and crossloading slopes on east, north and west facing aspects as well as loading slopes below rocky or steep headwalls well below the ridgetops.  Windslabs range from very stiff to soft today and from a few inches to over a foot thick. Some of these windslabs formed on the crusts that developed during our last high pressure. Look for clues like cracking and collapsing as well as other obvious signs of windslab like a textured or scalloped snow surface or pillows and drifts as you are moving through the mountains today.  Additional snowfall on Friday evening also did a great job camouflaging some of these obvious clues so pay attention to the way the snow feels as you travel today, if you encounter a hollow, punchy, or drummy feeling snow surface you are on windslab.  Snowmobiles may have more of an affect on these slabs than skiers where they are more dense or firm. Wind slabs often let you get well out on to them before you are able to trigger them trapping you in the middle of the slab when it is triggered. 

Saturday, 02/20/2016 - 08:30 Above Cascade, ID Lookout Peak, West Mountain wind slab Natural.

 

Avalanche Problem 2: Deep Slab
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The pesky New Year's buried surface hoar still lingers deep in our snowpack. It is located mid-slope on northwest through east aspects above 7,000 feet and will most likely be with us for the rest of the snow riding season. Pit results and stability testing point toward less likelihood of triggering, but if triggered we are still talking about a potentially unsurvivable hard slab avalanche. Take the time to carefully assess terrain choices on the north half of the compass today and throughout the rest of the season. This layer is especially dangerous in 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. This is the same layer that was the cause of the fatal avalanche on January 31st. A persistent,deep weak layer such as this is a low probability, but HIGH CONSEQUENCE scenario.  

Avalanche Problem 3: Loose Wet
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The Sun, South winds, and a warming trend will all contribute to the rising danger of loose, wet avalanches today. More than likely, you will see these loose wet slides, and roller ball activity on steep and rocky slopes that receive direct solar radiation. As the day progresses, the danger will follow the compass from East to West...giving us the highest danger this afternoon on Southwest slopes...If you are sinking past your boot tops on a South aspect, it may be time to find a cooler, shadier slope to play on?

recent observations

We had a report of a decent sized natural avalanche near Marge Lake on Friday, and one off of West Mountain on Saturday.  If you do trigger an avalanche or see avalanche activity, please take the time to send us a short report and a photo with as much of a description as possible.  You can email avalanche info to us at: forecast@payetteavalanche.org or plug it into our Observations page on the website . Your help is greatly appreciated!

weather

Sunny skies, and a high of 32 in the upper elevations will crank up the heat, beginning a warming trend. Winds will blow out of the South around 5-15 MPH.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Tuesday Tuesday Night Wednesday
Weather: Sunny, with a high near 36. Calm wind becoming south around 6 mph in the afternoon. Mostly clear, with a low around 14. Light and variable wind. Partly sunny, with a high near 40. Calm wind.
Temperatures: High 36 deg. F. Low 14 deg. F. High 40 deg. F.
Wind direction: South Variable Calm
Wind speed: 5-8 Light Calm
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Tuesday Tuesday Night Wednesday
Weather: Sunny, with a high near 32. South wind 5 to 15 mph. Mostly clear, with a low around 20. Southwest wind 10 to 16 mph. Increasing clouds, with a high near 39. Southwest wind 5 to 9 mph.
Temperatures: High 32 deg. F. Low 20 deg. F. High 39 deg. F.
Wind direction: South Southwest Southwest
Wind speed: 5-15 10-16 5-9
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

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.