THIS AVALANCHE ADVISORY EXPIRED ON January 14, 2016 @ 6:35 am
Avalanche Advisory published on January 13, 2016 @ 6:35 am
Issued by Dave Bingaman - Payette Avalanche Center
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The avalanche danger remains LOW today on non wind affected aspects. In steep upper elevation, wind loaded areas, a skier or rider could trigger a shallow wind slab and/or get caught in a fast moving sluff. The avalanche danger will rise today with new snow and new wind deposited snow falling on a variety of old snow surfaces. 

How to read the advisory


  • Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Wind Slab
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You are most likely to find wind slabs (soft or hard) on or near ridgetops scattered from the E through the N and back to the SW aspects.  Winds have been gusting into the high 20 and low 30 MPH range for 2 days easily moving the recycled powder around and scouring other areas. Visually, the areas of wind slab will likely have a different texture and feel hollow or punchy. In the wrong spot (shallow rocky, thin areas) these wind slabs may be resting on faceted or unconsolidated snow below and have the potential to become a nasty hard slab avalanche. This potential should be enough to keep you on your toes even though we are in a period of LOW danger. It should also be enough to keep you from skiing rocky areas that have visual evidence of recent wind effect or a much thinner snowpack. Snowmobiles are more likely to trigger this wind slab than a skier especially if you are high marking or making successive side hill runs through steep wind loaded areas. Be aware of how deep your track is digging and if you feel a sudden change in that depth, that means you have just cut through into the less consolidated snow below the more firm wind slab. We found a small natural wind slab avalanche in the upper reaches of the Cly Creek drainage yesterday. The debris pile was big enough to partially bury a skier or rider.

Avalanche Problem 2: Storm Slab
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The West Central is under a Winter Storm Advisory for today and into the night tonight.  This storm will be accompanied by gusty S and SW winds.  The combination of moderate accumulations, wind and a variety of old snow surfaces will increase the avalanche danger as the snow accumulates.  Take the time to check the interface and the bond between the old snow and the new snow as well as what sort of old snow surface is under the new snow. We have developed a healthy and relatively widespread layer of Surface Hoar and Near Surface facets(recycled powder) which has done a great preserving the snow since the Christmas storms.  We have also developed some slick crusts on sun affected aspects, these layers will provide a good bed surface and weak layer for new avalanche activity over the next few days.

recent observations

There are a variety of old snow surfaces that will become our next weak layers out in the mountains right now.  Surface hoar and Near Surface Facet formations are widespread in wind protected areas.  Slick melt/freeze or sun crusts are fairly widespread on the Southerly and West facing aspects as well.  All of these have the potential to create a buried weak layer as the new snow accumulates over the next few days, especially in wind loaded areas where they will be buried much deeper. Pay attention to the old snow new snow interface if you are on slopes steep enough to slide as the new snow piles up. We found a decent sized  and new natural slide in the Cly Creek drainage yesterday that had released in wind deposited snow.  If you see or trigger an avalanche over the next few days, please let us know.  You can enter a brief or detailed observation of what you saw on our website or just send us an email at: forecast@payetteavalanche.org

 

weather

Several inches of snow are forecasted throughout the day today with gusty S and SW winds in the upper elevations getting close to 40mph. Winds should ease later in the day with snow continuing through most of the night tonight. Total accumulations will range from 5-9 inches with some upper elevation areas receiving slightly more.  Look for light snow through Thrusday with another round of moisture entering our area Thursday night.

 

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow. High near 33. South southeast wind 5 to 10 mph. Chance of precipitation is 80%. Total daytime snow accumulation of 2 to 4 inches possible. Snow, mainly before 11pm. Low around 23. South southeast wind 5 to 9 mph. Chance of precipitation is 90%. New snow accumulation of 1 to 3 inches possible. A 30 percent chance of snow, mainly before 11am. Mostly cloudy, with a high near 27. Calm wind becoming south southeast around 5 mph in the afternoon. New snow accumulation of less than one inch possible.
Temperatures: 33 deg. F. 23 deg. F. 27 deg. F.
Wind direction: S/SE S/SE S/SE
Wind speed: 5-10 5-9 5
Expected snowfall: 2-4 in. 1-3 in. Trace in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow. High near 31. Windy, with a south southwest wind 24 to 30 mph, with gusts as high as 39 mph. Chance of precipitation is 80%. Total daytime snow accumulation of 3 to 5 inches possible. Snow. Low around 19. Breezy, with a south southwest wind 16 to 21 mph becoming northwest 5 to 10 mph in the evening. Chance of precipitation is 80%. New snow accumulation of 2 to 4 inches possible. A 30 percent chance of snow, mainly before 11am. Mostly cloudy, with a high near 25. Northwest wind 6 to 11 mph becoming light and variable. New snow accumulation of less than one inch possible.
Temperatures: 31 deg. F. 19 deg. F. 25 deg. F.
Wind direction: S/SW S/SW changing to NW NW
Wind speed: 24-30 gusting to 39 16-21 becoming 5-10 6-11 calming throughout the day
Expected snowfall: 3-5 in. 2-4 in. less than 1 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.