THIS AVALANCHE ADVISORY EXPIRED ON January 16, 2016 @ 7:24 am
Avalanche Advisory published on January 15, 2016 @ 7:24 am
Issued by George Halcom - Payette Avalanche Center
bottom line

New snowfall over the last 48 hours, and moderate to strong winds have caused the avalanche danger to rise to CONSIDERABLE above 7,000 feet on all steep wind loaded slopes. Fresh wind slabs have formed on a variation of different surfaces on all leeward slopes. If traveling above 7,000 feet human caused avalanches are likely. Below 7,000 feet the danger is MODERATE due to wind slabs.

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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The winds have howled during the last storm that caused widespread natural avalanches yesterday, So be on the look out for wind slabs in likely and unlikely places (below cliffs, cross-loaded slopes). These new wind slabs are going to be reactive on all leeward (downwind) aspects over 30 degrees that have obvious signs of wind loading (smooth rounded pillow like snow surface) and could range from 6 inches to 3 feet in depth. The tricky part about our current conditions, is that due to the high winds yesterday, these wind slabs could be located mid-slope on steep open faces. This will allow you to get half way down a slope before getting into trouble. 

Avalanche Problem 2: Persistent Slab
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We have buried one of the nastiest layers known to snow. Surface hoar that formed during our last extended cool, dry weather is now buried 33CM/ 1 foot down, and is showing potential for propigation. Natural avalanches went yesterday on many wind loaded Northern and Eastern slopes...This problem layer has the potential to linger for a while in our snowpack, and is a very common factor in avalanche fatalaties...take the time to dig, and evaluate every slope above 30 degrees, and stay far fromthebottom,or run-outof steep slopes!

Avalanche Problem 3: Loose Dry
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This foot of new, dry, cold snow has the potential to run with you, or sluff. Pay attention to your sluff it can knock you off your feet, and put you into places you would rather not be.

advisory discussion

It is game on for avalanche conditions in the backcountry! Slopes over 30 degrees warrent respect and patience. With 12 inches of new snow and the perfect making of an avalanche (surface hoar/facets with a new slab on top) these are prime condintions to get into trouble if you do not carefully evaluate the snowpack and make conservative decisions. Keep to low angle slopes in sheltered terrain today and enjoy the cold low angle powder.

recent observations

Yesterday we toured a large chunk of the advisory area, and we were not suprised to find fresh evidence of natural avalanches on mainly Northern aspects that went on a layer of buried surface hoar (33CM Down) that formed during our cool dry spell. The winds overloaded this layer, and it is still buried, waiting for a trigger in many other places. More snow will ramp up the danger on this persistant weak layer. We had simiar reports from Tamarack, but also on South aspects there. 

weather

Expect the Wset winds to calm down today, and a high temperature near 27 in the upper elevations, and just a bit warmer in McCall...our next round of snow should start on Saturday.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Scattered snow showers. Cloudy, with a high near 28. Light south southeast wind. Chance of precipitation is 40%. Total daytime snow accumulation of less than a half inch possible. A 30 percent chance of snow. Cloudy, with a low around 19. Light south southeast wind. New snow accumulation of less than a half inch possible. Snow. High near 30. South wind around 5 mph becoming calm in the afternoon. Chance of precipitation is 90%. New snow accumulation of 1 to 3 inches possible.
Temperatures: High 28 deg. F. Low 19 deg. F. High 30 deg. F.
Wind direction: SE SSE South
Wind speed: Light Light 5MPH-calm
Expected snowfall: less than half in. less than half in. 1-3 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Scattered snow showers. Cloudy, with a high near 27. West wind around 5 mph becoming calm in the morning. Chance of precipitation is 50%. Total daytime snow accumulation of less than one inch possible. A 40 percent chance of snow. Cloudy, with a low around 19. Light and variable wind becoming south southwest 5 to 10 mph after midnight. New snow accumulation of around an inch possible. Snow. High near 31. South southwest wind 13 to 16 mph. Chance of precipitation is 90%. New snow accumulation of 3 to 5 inches possible.
Temperatures: High 27 deg. F. Low 19 deg. F. High 31 deg. F.
Wind direction: West S/SW SSW
Wind speed: 5MPH 5-10 13-16
Expected snowfall: Less than 1 in. 1 in. 3-5 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.