THIS AVALANCHE ADVISORY EXPIRED ON December 31, 2016 @ 7:00 am
Avalanche Advisory published on December 30, 2016 @ 7:00 am
Issued by Dave Bingaman - Payette Avalanche Center
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The Avalanche Hazard is Moderate above 6000 ft today.  Gusting and variable winds have created areas of wind slab on many upper elevation and wind exposed slopes throughout the last few days. Watch for wind sculpted or stiff pockets of snow on windward slopes and drifts or pillows on leeward slopes/smaller terrain features that can catch wind blown snow. Expect additional wind loading today with SW gusts into the upper 20 mph range becoming N later in the day.

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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S and SW winds over the last few days have been higher than forecasted in the upper elevations with rapid loading occurring through the Monday/ Tuesday storm and continuing through yesterday.  We watched large plumes of snow streaming off the higher peaks in the area around Secesh Summit yesterday.  The winds yesterday were also surprisingly variable as they ricocheted through drainages with spindrift and blown snow down low on many middle elevation aspects.  Most of the windblown snow yesterday accumulated on the Northerly aspects falling on the older windslabs deposited Monday/Tuesday. Some of these older windslabs ran naturally on Tuesday and were able to "step down" into deeper layers below.  If you are unlucky enough to find one of these overloaded areas today, you could be looking at a 1-3 foot deep windslab of varying stiffness. Watch for sculpted or stiff wind board on the windward aspects and hollow feeling or sounding pillows and drifts on leeward aspects.  You should also be aware that due to the high velocity of the wind that these features may be found well below the ridgelines on leeward terrain.

Avalanche Problem 2: Loose Dry
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Having an abundance of Loose, Dry snow is a great problem to have.  While things have already settled out from the storm early this week quite a bit, there is still an abundance of dry, cohesion less snow in protected areas.  If you are skiing or riding in steeper wind protected terrain, be aware that these small sluffs can pile up quickly in terrain traps or steer you in directions that you may not want to go if you become involved or entrained in them.  Use good travel protocols-ONE AT A TIME on slopes steep enough to slide and keep your eyes on your partners.

advisory discussion

PAC still has room for both skiers and snowmobilers in our upcoming Intro to Avalanches class on Jan 6 and 7, registration by email is required.

Friends of the Payette Avalanche Center needs YOU! Come join us on Tuesday January 3rd at Idaho First Bank in McCall at 6 pm for an annual membership meeting. This meeting is open to the entire snow loving community,  and we need to hear from you on how the Payette Avalanche Center should grow into the future.

Did you know: Only a small portion of our operating budget comes from the Forest Service, we RELY on the the Friends of  the Payette Avalanche Center to help finance the forecasts that you use and the equipment we use to gather the information.  Our forecast sleds are overdue for replacement and we rely on these as important tools to provide reliable avalanche advisories to the public...don't let your local avalanche center end up with a pile of melted metal, plastic and rubber on the side of the road! Come out and support your FRIENDS and get involved Tuesday night or make a tax deductible donation online.

recent observations

We toured the Eastern edge of Squaw Point yesterday and were surprised by the intensity of the upper elevation winds. LARGE plumes of wind blown snow were visible on most of the peaks to our East in the 20 Mile drainage and near Storm and Victor Peaks.  Bob Dylan said it best: " you don't need a weatherman to know which way the wind blows" so a word to the savvy backcountry traveler right now is pay attention to the the obvious signs.  High winds are one of the Red Flags and right now they are dumping snow over ridges into leeward terrain.  

We were able to get  multiple failures (CTM scores) in windloaded terrain in our test pits on 2 different wind layers in the upper 1/3 of the snowpack.  We also had an ECTN in the same pit suggesting little propagation potential in that location.  Earlier this week these same layers produced a natural avalanche cycle mid storm as they overloaded the bond of the new and wind blown snow to the older snow below.  Some of the naturals that we observed on Tuesday had "stepped down" to a slightly deeper layer below as they pushed downhill. These test scores and the recent avalanches tell me to keep an eye on the snowpack in steep, leeward terrain(mostly NE, N and NW terrain) and avoid windloaded terrain for the next few days as winds die down and these windslabs have a chance to settle out.

weather

Today you can expect to see fog in the lower valleys with snow showers throughout the day in the mountains.  Light accumulations of snow today and a cold front entering the area tonight will mark the beginning of the coldest temperatures of the winter so far.  Temperatures next week will fall as an Arctic air mass establishes itself over the Western US with temperatures 20-30 degrees below normal. Dry, cold weather will stick around through next weekend. Winds will begin as SW today and shift to N/NE later in the day.  Expect wind speeds in the upper elevations approaching 30 today and dropping back into the 20 mph range tonight with slightly more snow in the Northern portion of the advisory area.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Snow Showers Partly Cloudy Sunny
Temperatures: 24 deg. F. -4 deg. F. 16 deg. F.
Wind direction: Variable then NW NNE NE
Wind speed: 6 6 5
Expected snowfall: 1 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Snow Showers Partly Cloudy Sunny
Temperatures: 24 deg. F. 7 deg. F. 22 deg. F.
Wind direction: SW then N in the PM NNE NNE
Wind speed: 8-13 9-14 6-11
Expected snowfall: 1-2 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.