THIS AVALANCHE ADVISORY EXPIRED ON December 15, 2015 @ 6:01 am
Avalanche Advisory published on December 14, 2015 @ 6:01 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

Boom it's winter! Local Mountains picked up 18+ inches of new snow yesterday! Expect Considerable hazard in wind loaded terrain.  With winds shifting across the compass, skiers and Snowmobilers may trigger wind slabs on mid to upper elevation slopes over, or approaching 35 degrees. On protected slopes you may also trigger smaller slabs within the new snow layers or at last week's rain crust. Gusting N winds will continue to form new wind slabs on leeward terrain today.

How to read the advisory


  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Gusty winds were easily transporting the new snow yesterday and increased last night.  Expect to find newly formed wind slabs on mulitple upper elevation aspects today. New slabs may have formed in gullies or other small terrain features as well as open, exposed terrain. Use extra caution as you approach any steep wind affected terrain today as new slabs may be soft or hard depending on the amount and duration of wind that formed them. Wind slabs are tricky beasts as they sometimes let you get fully committed to a slope before you find them. Based on the amount of new snow these slabs could be a few inches or a few feet thick depending which aspect you are on. With gusty N winds forecasted for today and tonight expect to see additional wind slab formation throughout the next 24 hours.

Avalanche Problem 2: Storm Slab
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With nearly 2 feet of fresh snow and fluctuating temperatures over the last few days, instabilities are likely to have formed within the new snow layers.  Ski cuts on test slopes are a great way to test for these. With a stout ice crust below all of the new snow, you may find all or part of the new snow ready to fail on steeper wind protected slopes. 

advisory discussion

Below normal temperatures over the next few days with a chance of snow prior to another round of moisture  starting on Wednesday. Blustery Northerly winds will keep the wind chill close to 0.

recent observations

The new snow came in with a fair amount of wind which shifted across the left side of the compass yesterday. Expect to find wind transported snow and new wind slabs on all exposed leeward slopes.  As the new snow piled up yesterday, the temperatures increased creating subtle storm slabs within the new snow layers. Absolutely phenomenal powder conditions for riders and skiers. We didn't get any avalanche reports from our advisory area yesterday but with the  heavy accumulation and the wind it's still going to be head's up conditions in the mountains today.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: No data yet deg. F.
Max. temperature in the last 24 hours: deg. F.
Average wind direction during the last 24 hours:
Average wind speed during the last 24 hours: mph
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weather
 
Scattered snow showers. Cloudy, with a high near 22. Blustery, with a north wind 16 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 50%. New snow accumulation of 1 to 2 inches possible.
Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: Scattered snow showers. Cloudy, with a high near 29. North northwest wind 6 to 9 mph. Chance of precipitation is 30%. Total daytime snow accumulation of less than a half inch possible. A 20 percent chance of snow showers before 11pm. Mostly cloudy, with a low around 16. North wind 6 to 8 mph. A 20 percent chance of snow showers before 11am. Partly sunny, with a high near 26. North wind around 6 mph.
Temperatures: 29 deg. F. 16 deg. F. 26 deg. F.
Wind direction: N-NW N N
Wind speed: 6-9 6-8 6
Expected snowfall: 1 inch in. Trace in. Trace in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: Scattered snow showers. Cloudy, with a high near 22. Blustery, with a north wind 16 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 50%. New snow accumulation of 1 to 2 inches possible. A 50 percent chance of snow showers, mainly before 11pm. Mostly cloudy, with a low around 14. Wind chill values between -1 and 5. Blustery, with a north wind 16 to 21 mph, with gusts as high as 30 mph. New snow accumulation of less than one inch possible. A 20 percent chance of snow showers before 11am. Partly sunny, with a high near 23. Wind chill values between -1 and 9. North wind 11 to 16 mph.
Temperatures: 22 deg. F. 14 deg. F. 23 deg. F.
Wind direction: N N N
Wind speed: 16-22, Gusts to 31 16-21, Gusts to 30 11-16
Expected snowfall: 1-2 in. 1 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.