THIS AVALANCHE ADVISORY EXPIRED ON January 28, 2017 @ 6:07 am
Avalanche Advisory published on January 27, 2017 @ 6:07 am
Issued by Dave Bingaman - Payette Avalanche Center
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The Avalanche Danger today is Moderate, human triggered avalanches are possible.  Buried Surface Hoar and small grained Faceted snow may be found in lower elevations or areas that were sheltered from high winds before they got buried.  Wind slabs of varying thickness and hardness are present near ridgelines and on almost all exposed terrain. Use good travel techniques, ski or ride one at time and keep your eyes on your partners if you are in steep terrain.

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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We have been impressed this week with the amount of  wind effect near the ridgelines on almost all aspects due to 30+  MPH winds out of several directions over the last 10 days.  The most recent NE winds have created firm wind slabs that, in most places, don't crack any further than your skis but are definitely sensitive to the weight of skiers and sledders.  We have also seen some recent Cornice growth on Northerly aspects, stay clear from the overhanging edges which can break back further than you may think.

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 or into buried persistent weak layers in some areas. If this scenario played out it could cause a much larger and hard to survive avalanche. 

Evaluate terrain choices carefully today. Wind and its effects have been variable throughout the mountains recently. Look for signs of wind effected terrain as you travel and use safe travel protocols in avalanche terrain.  Ride or ski one at a time on steep slopes and keep your eyes on your partners.

Avalanche Problem 2: Persistent Slab
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Several Persistent Weak Layers exist in our snowpack right now.  Well developed Surface Hoar and Small Grained Facets(NSF) and on some Southerly slopes crusts all got buried in last week's storm.  In some areas these layers are nearly 2 feet down and remain a problem.  In most areas these layers were either destroyed by the high winds that accompanied the storm or were impacted by the heavier, wetter snow and are no longer a problem.  

While the probability of triggering an avalanche on one of these layers has become less likely,  you are still more likely to trigger these layers in certain areas.  Lower elevation, wind protected slopes or areas of  areas of dense trees are still harboring these layers and they have proven to be VERY WEAK were they were preserved.  George and I have seen significant collapsing, cracking and a snowpack that fails on isolation(while attempting to test) in our travels this week.  Areas out of Bounds at Tamarack below 6500 feet still have a very weak layer of Buried Surface Hoar while higher up in treed areas we found moderate failures on the old snow surface where Near Surface Facets(recycled powder) were formed.  We found similar results in the Lick Creek area and have had reports that echoed the same results from Big Creek Summit and areas to the South of the PAC Advisory area.

Buried Surface Hoar tends to propagate easily when triggered and has been responsible for most of the Avalanche Fatalities in Idaho. The only way you are going to know if it is in the snowpack is by digging down to the old snow interface with either your hand or a shovel. Buried Surface Hoar will show up as an obvious grey line or strip in a clean wall or the cut face of your pit.

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

Help PAC get a clearer picture of what's happening (or not happening) where you are riding or skiing.  Observations can be submitted on our website easily and you can upload photos and describe conditions by clicking on the fields or by writing a short description.  All info is good info, photos of wind effected or pure fluff can help us get a handle on all the nooks and crannies throughout our advisory area.  You can also email us at:  forecast@payetteavalanche.org if you have observations you want to share.  Areas outside of our Advisory area can be found on the Observation Submission page, we welcome obs from Big Creek, Mores Creek(Idaho City) and other outlying areas.  Use our site as a community forum to share conditions and snowpack info, that is why it exists.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 17 deg. F.
Max. temperature in the last 24 hours: 17 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: 4 mph
Maximum wind gust in the last 24 hours: 14 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 86 inches
weather

Today through Saturday...A strong ridge of high pressure and a significant inversion continues to build across the Pacific Northwest.  The ridge of high pressure is expected to remain overhead and strengthen through Saturday. This will solidify the building inversion and lock cold air and low level moisture into the valleys. Fog and stratus will be the norm during this period, with minor improvements in visibility during the day and a return to fog for many locations overnight. Winds will be light under the inversion, and for most mountain and ridge tops as well. Temperatures will remain well below average for all lowland areas. With the ridge in place and very limited moisture there is little chance of precipitation across the area. A few snow flakes will be possible under the persistent valley stratus, however, accumulation will generally be negligible.

Saturday night through Thursday,..Upper level ridge is at its maximum amplitude Saturday night, producing a strong inversion over the western U.S. Heights aloft begin to fall Sunday and by Monday the weakened ridge axis has retrograded to just off the coast. This puts us in dry WNW flow aloft as a high-over-low block becomes established between 135W and 140W. The low begins to slowly work eastward toward the coast Wed, pushing the ridge axis into Oregon, and potentially bringing moisture to the PacNW. As we get into Thu, the upper low opens up and moves onshore, increasing wind fields and increasing the chance for the inversion to break down. Models differ on the timing and placement of the moisture in the long term (as they almost always do), so will leave current forecast alone as we already have a chance of precip mainly in the north.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Areas of Dense Fog then Mostly Sunny Areas of fog and Partly Cloudy Areas of fog then Mostly Sunny
Temperatures: 23 deg. F. 4 deg. F. 24 deg. F.
Wind direction: Calm Calm Calm
Wind speed: 0 0 0
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Mostly Sunny Partly Cloudy Mostly Sunny
Temperatures: 24 deg. F. 13 deg. F. 30 deg. F.
Wind direction: NNW W/NW NW
Wind speed: Around 5 then light Light 3-6
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.