THIS AVALANCHE ADVISORY EXPIRED ON December 25, 2015 @ 6:51 am
Avalanche Advisory published on December 24, 2015 @ 6:51 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The Avalanche Hazard is Moderate today. Pockets of Considerable Hazard exist near ridge tops where S and SW winds have created sensitive wind slabs in the new snow. Wind slabs may also be encountered on E or W facing slopes especially in gullies or other small scale terrain features that catch the blowing and drifting snow. Overall, the new snow is bonding well 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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Parts of the PAC advisory area saw sustained winds in excess of 35 mph on Monday with gusts climbing over 50 mph. Yesterday, we observed cornices growing on North aspects, and continued wind loading from the SW. With the amount of snow we received, that equals some serious wind transport.  Be aware that you could trigger a shallow or deep wind slab on upper elevation wind loaded slopes for the next few days. 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.

Avalanche Problem 2: Storm Slab
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The West Central Mountains have recieved 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.  Bottom line is that you may still trigger one of these instabilities in the new snow on unsupported, steep rollovers or other convex slopes. See the pit tests from Tuesday for depths and scores.

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 yesterday on steeper slopes and while they are moving 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 Holiday Bowl, SW of Squaw Point. We noticed in protected areas that the snow was traveling much deeper. The new snow is bonding fairly well to the old snow. We dug a test pit at 7,000 feet on a north aspect and found 260cm of snow that was setting up nicely. We had a CT14Q2 @65cm that failed to propigate in an ECTN14 Q3 Broken. Cold temperatures have created nice fluffy snow on top of snowpack that continues to consolidate.

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
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weather

Light snow is forecasted to finish today, making way for a high pressure building over the weekend and pushing the next few storms to the South of the West Central Mountains. Sunshine will be the theme to come!

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Thursday Thursday Night Friday
Weather: Snow showers likely, mainly after 11am. Cloudy, with a high near 23. Calm wind becoming west northwest around 5 mph in the afternoon. Chance of precipitation is 60%. Total daytime snow accumulation of around an inch possible. A 20 percent chance of snow showers before 11pm. Partly cloudy, with a low around 5. North northwest wind around 5 mph becoming calm in the evening. Partly sunny, with a high near 20. Calm wind becoming west northwest around 5 mph in the afternoon.
Temperatures: 23 deg. F. 5 deg. F. 20 deg. F.
Wind direction: WNW NNW WNW
Wind speed: 5MPH 5MPH-Calm Calm becoming WNW
Expected snowfall: 1 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Thursday Thursday Night Friday
Weather: Snow showers likely. Mostly cloudy, with a high near 19. Wind chill values between -1 and 9. Southwest wind 6 to 13 mph. Chance of precipitation is 60%. Total daytime snow accumulation of 1 to 3 inches possible. A 20 percent chance of snow showers. Mostly cloudy, with a low around 9. Wind chill values between -3 and 7. North northwest wind 6 to 8 mph. A 20 percent chance of snow showers. Partly sunny, with a high near 18. Wind chill values between -4 and 6. Northwest wind around 9 mph.
Temperatures: 19 deg. F. 9 deg. F. 18 deg. F.
Wind direction: SW NNW NW
Wind speed: 6-13 6-8 9
Expected snowfall: 1-3 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.