THIS AVALANCHE ADVISORY EXPIRED ON January 27, 2017 @ 7:13 am
Avalanche Advisory published on January 26, 2017 @ 7:13 am
Issued by George Halcom - Payette Avalanche Center
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The avalanche danger is Moderate  today at all elevations on slopes over 30 degrees due to human triggered avalanches being possible. Surface hoar is buried between 1-2 feet, in isolated areas that stayed sheltered from the winds. Sensitive wind slabs can be found near ridgelines.

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Persistent Slab
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Winds tend to vary in the mountains, and finding and triggering this weak, potentially dangerous layer (Buried Surface Hoar) may be possible in areas that were sheltered from the wind, where we are still finding a preserved, VERY WEAK layer of surface hoar and near surface facets that is supporting one to two feet of snow. We have been finding it near the bottom of drainages where you might expect. Be suspect of any wind protected areas. 

Yesterday, in the NW drainage of Sawtooth Peak around 6700 feet we found the buried surface hoar low in the flatsr...Tuesday, North of Tamarack, Dave and I had shooting cracks in the upper 40 cm of the snow while starting to dig a pit at abot 5900 ft, ENE Tamarack Falls-West Mountain North of Tamarack Resort. In the pit, we found a very weak layer of surface hoar 40 cm down that failed in compression as soon as he put his shovel on it, and it failed in an ECT as soon as we cut/isolated it.

Although backcountry travelers have not reported any incidents of triggering this weak layer, stability tests are alarming, and it obvious that this layer has little to no strength. You should still be very weary of the weak layers energy and ability to propagate (see Dave's video of propagation saw test). This is another low probability/ high consequence problem that may linger? Use safe travel protocols in avalanche terrain, and expose only one at a time whenever possible. 

While out in the mountains, Quickly dig down and look for this 'grey' looking line in the snowpack. Its obvious and shallow enough that you can did down with your hand. We are finding it on east, northeast, north, northwest, and west aspects in low and middle elevations that were protected from the winds that accompanied last weeks storm. Where are you finding it, or better yet, not finding it? We want to know, submit a quick observation on our site so that we can share with others as quick as possible! 

***Surface Hoar and faceted snow layers are responsible for more avalanche accidents and fatalities than all other types of avalanches combined.

 

Contest: First person to send a picture/observation of surface hoar in our current snowpack gets a free FRIENDS OF PAYETTE AVALANCHE CENTER t-shirt!

 

Avalanche Problem 2: Wind Slab
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Winds have died down in the last 24 hours to a light SW-West flow, but previous 30 MPH Northeast winds, and snow have created some fresh, shallow wind slabs that are sensitive to the weight of a skier, which could be bad in the right spot?

Yesterday, touring up the NW drainage of Sawtooth Peak, near the ridgelines we were impressed at the detail of etching in the snow surface from the wind. The recent NE winds have created quite firm wind slabs that, in most places, don't crack any further than your skis ...I was able to get a small wind slab to release with a ski cut about 3 inches thick on a NE aspect of the ridgline around 7700 feet. 

Lurking below the new wind affected snow, still lingers older stiffer (harder to trigger) wind slabs. Be conscious of  the ability of these older slabs to 'step down' into older layers of snow, and even cause a failure of our buried persistent weak layers. If this scenario played out it could cause for a large, possibly fatal avalanche. 

Evaluate terrain choices carefully today. Winds tend to vary in the mountains. Look for signs of wind effected terrain, Use safe travel protocols in avalanche terrain, and expose only one at a time whenever possible.We have seen some recent growth of Cornices on North aspects also...stay clear from the overhanging edges which can break back further than you may think.

advisory discussion

Remember your information can SAVE LIVES!! If you see anything we should know about, please participate in the creation of our own community avalanche advisory by submitting snow and avalanche conditions. It's okay if you leave some fields blank, just fill out what you know and/or submit photos. You can  also email us at  forecast@payetteavalanche.org.

The Friends of the Payette Avalanche Center (FPAC) needs YOU! We are in desperate need of more user support and financial assistance. The avalanche forecast is not a guaranteed service, and is in jeopardy of dwindling down to only a couple of days a week in the near future. Please help if you can by clicking the DONATE tab above. If you value this life saving information, make a donation or help the FPAC in raising funds for the future.

 

Snowmobiler/Snowbiker Travel Restrictions:  a quick reminder that the Granite Mountain Area Closure is now in effect.  In addition there are other areas on the Payette National Forest that are CLOSED to snowmobile traffic including Jughandle Mt east of Jug Meadows, Lick Creek/Lake Fork Drainage (on the right side of the road as you are traveling up canyon), and the area north of Brundage Mt Ski area to junction "V" and along the east side of Brundage and Sergeants' Mts. with the exception of the Lookout Rd( junction "S").  Please respect these closures and other users recreating in them.  Winter Travel Map(East side). You can download the map to the AVENZA app on your phone, and know your exact location while you are out riding. 

recent observations

Yesterday, touring up the NW drainage of Sawtooth Peak, we found good stability while skiing and also in our pits up higher, but in the flats, low around 6700 feet we were able to find a well preserved layer of surface hoar. Near the ridgelines we were impressed at the detail of etching in the snow surface from the wind. The recent NE winds have created quite firm wind slabs that, in most places, don't crack any further than your skis most of the time...I was able to get a small wind slab to release with a ski cut about 3 inches thick on a NE aspect of the ridgline around 7700 feet. 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 10 deg. F.
Max. temperature in the last 24 hours: 13 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 3 mph
Maximum wind gust in the last 24 hours: 11 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: inches
weather

An inch of new snow fell overnight at Brundage. Today it will be partly sunny with a 20 % chance of snow showers after 11 am in the mountains, with a high near 23 in McCall, and a high of 20 in the upper elevations. Winds will be light in the valley with North-northwest winds near the ridgetops around 6 mph. No new snow expected. High pressure along and another inversion will start to set in this evening, bringing us clear skies and warmer temperatures in the upper elevations than in the mountains.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Thursday Thursday Night Friday
Weather: Partly sunny, with a high near 23. Light and variable wind. Patchy fog after 11pm. Otherwise, partly cloudy, with a low around 0. Wind chill values between -3 and -8. Light and variable wind. Patchy fog before 11am. Otherwise, mostly sunny, with a high near 21. Wind chill values between zero and 10. Calm wind.
Temperatures: High 23 deg. F. low 0 deg. F. High 22 deg. F.
Wind direction: Variable Variable Calm
Wind speed: Light Light Calm
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Thursday Thursday Night Friday
Weather: A 20 percent chance of snow showers before 11am. Partly sunny, with a high near 20. North northwest wind around 6 mph. Partly cloudy, with a low around 11. North wind around 6 mph. Mostly sunny, with a high near 27. North northwest wind around 6 mph becoming west in the morning.
Temperatures: high 20 deg. F. low 11 deg. F. high 21 deg. F.
Wind direction: North-northwest North North-northwest becoming West
Wind speed: 6 6 6
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.