THIS AVALANCHE ADVISORY EXPIRED ON January 1, 2017 @ 6:53 am
Avalanche Advisory published on December 31, 2016 @ 6:53 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The Avalanche Hazard is Moderate on upper elevation slopes today.  Gusting and variable winds have created areas of wind slab on many wind exposed slopes throughout the last few days. Watch for wind sculpted or stiff pockets of windslab on windward slopes and drifts or pillows on leeward slopes and smaller terrain features that can catch wind blown snow. Expect additional wind loading today with SW gusts in the upper teens to 20 mph range throughout 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
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

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 Thursday and continued to see gusts into the 20+ range yesterday and last night.  Most of the wind transported snow has 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 rippled, chalky or hollow feeling/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.

 

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

Yesterday we picked up about 1-2 inches of very light density snow in the upper elevations during a short but intense precipitation event.  Winds were light through most of the day but picked up with gusts into the low 20mph range recorded overnight.  Variablity is the word right now.  South Valley observations reported good conditions and slightly better coverage for off trail travel.  In the northern areas, south facing terrain is thin and sketchy for sleds off trail still. We found a thin snowpack that varied wildly across the face of Jughandle yesterday with thin scoured sections and deep, powder shots where the wind has been depositing the snow.  We also found thin pockets of faceted snow that I was mentally mapping to remember when it starts snowing again.   Earlier this week we found a similarly variable snowpack near Squaw Point with well consolidated snow on the Southerly aspects and a mostly consolidated snowpack on the N aspects.  Windloading and wind effect are the common theme but areas of shallow, sugary snow can be found near rocky outcrops and around boulders within the snowpack...again, a good thing to keep in the back of your mind if you are in steep, rocky areas or as we get warmer, significant storms in the future.  The good news is that most of our problems are now concentrated in the upper elevations with good stability and snow quality in the middle elevations.

 

weather

A dense fog advisory exists today for the lower valleys with inverted temperatures remaining in place through the day and into tonight. A cold front will move into the West Central later tonight. With the cold front we will see a chance of light accumulations over the next and some very cold wind chills. Winds are expected to gust into 20 mph range today from the SW and S tonight and tomorrow adding to the wind slab problems that already exist.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Saturday Saturday Night Sunday
Weather: Fog in the am, sunny later in the day 30% chance of snow, partly cloudy Snow showers likely, cloudy
Temperatures: 16 deg. F. 3 deg. F. 16 deg. F.
Wind direction: ENE SE SSE
Wind speed: 5 then calm around 5 3-5
Expected snowfall: 0 in. Trace in. Around an inch in.
Granite Mountain at 7700 feet.
  Saturday Saturday Night Sunday
Weather: Sunny 40% Chance of snowshowers 90% Chance of snow
Temperatures: 24 deg. F. 8 deg. F. 13 deg. F.
Wind direction: SSW SSW S
Wind speed: 6-11 11-14 10
Expected snowfall: 0 in. 1 in. 1-3 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.