THIS AVALANCHE ADVISORY EXPIRED ON December 26, 2015 @ 6:47 am
Avalanche Advisory published on December 25, 2015 @ 6:47 am
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard is Moderate today. Pockets of Considerable Hazard still exist near ridge tops where S and SW winds have created fresh wind slabs in the new snow. Wind slabs may also be encountered on E or W facing slopes especially in gullies or other terrain features that catch the blowing snow. Overall, the new snow is doing a good job bonding to the older snow layers below creating a deep, dry, user friendly snowpack throughout the area.

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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Keep in mind that winds out of the SW this past week have been strong at times, gusting upwards of 50 MPH. Yesterday, we toured out to Sgt's Mountain, AKA Brundage Mountain Proper. 1-3 inches of snow was forecasted for yesterday, but Brundage ended up reporting 7 inches of new snow by 5 PM! It was snowing hard, and Moderate SW winds were pushing snow, adding to the growing cornices on East, and North aspects of the ridge, and creating fresh wind slabs that we noticed with our skis and poles. In areas that are protected from the wind, the snow was traveling much deeper. 

Be aware that you could trigger a shallow or deep wind slab on upper elevation wind loaded slopes. Cold temperatures do a great job preserving wind slabs and other weaknesses in the snowpack. You will be able to spot wind affected slopes literally from a mile away, look for sculpted or pillowed features as you make your terrain choices.

Granite's East Face on Tuesday showing the recent abuse from the SW winds.

Avalanche Problem 2: Storm Slab
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The West Central Mountains have received over 4 feet of snow in the last 7 days.  Overall the bonds between these different storm layers are pretty good, but we are still finding signs of instability at density changes within all this new snow. We found over 300cm (just about 10 ft) of snow Tuesday in a wind loaded N facing bowl near Fisher Creek Saddle.  Throughout the advisory area, we are seeing snow depths similar to what we would normally see much later in the season with most upper elevations in the 6-7 foot range.  

Avalanche Problem 3: Loose Dry
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Loose dry avalanches are a good problem to have, they mean you have deep, dry snow that is soft enough to move around when disturbed...most of the time these "sluffs" are pretty manageable. We saw a lot of moving snow over the past couple of days while skiing and riding on steeper slopes. While the snow moves with you relatively slow and small right now, they could still push you off course on a sled or skis.  Be aware of sluff potential and your options if you are riding or sliding in steep, confined terrain or terrain with obstacles or cliffs below you.

recent observations

Yesterday, we toured out to Sgt's Mountain, AKA Brundage Mountain Proper. 1-3 inches of snow was forecasted for yesterday, but Brundage ended up reporting 7 inches of new snow by 5 PM! It was snowing hard, and Moderate SW winds were pushing snow, adding to the growing cornices on East, and North aspects of the ridge, and creating fresh wind slabs. In areas that are protected from the wind, the snow was traveling much deeper. 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: no data deg. F.
Max. temperature in the last 24 hours: deg. F.
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Average wind speed during the last 24 hours: mph
Maximum wind gust in the last 24 hours: mph
New snowfall in the last 24 hours: inches
Total snow depth: inches
weather

Christmas is definitely white this year! The storm cycle has wound down, making way for Clear skies and cold temperatures. North West Winds will help keep temperatures cold through the weekend with slight chances of snow showers: most of the moisture will be to the South of our area. A ridge of High pressure will settle in on Saturday. 

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Isolated snow showers. Patchy fog before 11am. Otherwise, partly sunny, with a high near 20. Wind chill values between -4 and 6. Calm wind becoming northwest around 5 mph in the afternoon. Chance of precipitation is 20%. Areas of fog after 11pm. Otherwise, partly cloudy, with a low around -8. North northwest wind around 5 mph becoming calm in the evening. Areas of fog before 11am. Otherwise, sunny, with a high near 14. Wind chill values between -8 and 2. Light and variable wind.
Temperatures: 20 deg. F. -8 deg. F. 14 deg. F.
Wind direction: Calm to NW NNW Variable Direction
Wind speed: 5MPH 5MPH-Calm Light
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Isolated snow showers. Partly sunny, with a high near 17. Wind chill values between -12 and -22. North northwest wind around 8 mph. Chance of precipitation is 20%. A 10 percent chance of snow showers before 11pm. Partly cloudy, with a low around 2. Wind chill values between -1 and -11. North northwest wind 8 to 11 mph. Sunny, with a high near 15. Wind chill values between -3 and -13. North northwest wind 5 to 9 mph becoming southwest in the afternoon.
Temperatures: 17 deg. F. 2 deg. F. 15 deg. F.
Wind direction: NNW NNW NNW Becoming SW
Wind speed: 8 8-11 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.