Avalanche Advisory published on January 22, 2017 @ 7:29 am
This advisory is valid for 24 hours
Issued by - Kent May
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The avalanche danger is CONSIDERABLE above 7000 feet due to human triggered avalanches being likely. Our most recent storm cycle put down 18-21 inches of new snow that fell on a variety of old snow surfaces including well developed surface hoar, near surface facets and firm crusts.  In addition, a fresh crop of wind slabs will be found near the ridge tops on leeward and/or crossloaded slopes. 

How to read the advisory
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Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential. Natural avalanches possible; human-triggered avalanches likely. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

Avalanche Problem 1: Persistent Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    likely
    unlikely
  • Size ?
    large
    small
  • Trend ?
    Same

A relatively widespread layer of Surface Hoar and Near Surface Facets is now lying below the new snow.  We found this layer on Thursday 15-18 inches down in the middle elevations and in higher areas that were protected from the winds that accompanied this last storm cycle. Surface Hoar and faceted snow layers are responsible for more avalanche accidents and fatalities than all other types of avalanches combined.  This layer failed in many steep areas naturally as the new snow came in but is waiting for a trigger in many more.  This is a very tricky layer to predict or forecast for due to the variability and the uncertainty of where you will find it in the snowpack and throughout the mountains right now.  The only way you will know for sure is to dig in to the snow and look for the obvious grey line in the snow.  Whumphing or collapsing of the snowpack will let you know that you are in an area with buried surface hoar or faceted snow.  With this kind of variability, you will need to dig in lots of places as you travel.  Hand pits in lots of locations or 5 minutes with your shovel could save your life today.

The picture below shows a close up of the surface hoar layer at the height of the saw. This type of problem tends to linger for awhile.

 

        

Avalanche Problem 2: Wind Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    likely
    unlikely
  • Size ?
    large
    small
  • Trend ?
    Increasing Danger

With today's forecasted south winds expect to see any snow available for transport loading onto slopes on the north half of the compass making a thin new batch of wind slabs. Also, wind slabs were created in the upper elevations with the last storm cycle and winds in the upper 20 mph range common throughout most of the area.  Over the past week winds have swirled across the bottom of the compass from east to southwest creating the possibility of 1-3 foot deep wind slabs on the northern portion of the compass as well as east and west aspects.  These slabs may be resting on old wind slabs, a layer of surface hoar, or other faceted (loose grained) snow or on firm crusts.  Pay attention to the obvious signs of wind affected snow, rounded, sculpted, drifted or pillowy looking snow will let you know right where the wind deposited snow piled up.  Hollow sounding or feeling snow should tell you to find a different slope as well.

advisory discussion

Snowmobiler/Snowbiker Travel Restrictions:  a quick reminder that the Granite Mountain Area Closure is now in effect.  In addition there are other areas on the Payette National Forest that are CLOSED to snowmobile traffic including Jughandle Mt east of Jug Meadows, Lick Creek/Lake Fork Drainage (on the right side of the road as you are traveling up canyon), and the area north of Brundage Mt Ski area to junction "V" and along the east side of Brundage snd Sargeant's Mts. with the exception of the Lookout Rd( junction "S").  Please respect these closures and other users recreating in them.  Winter Travel Map(East side)

Remember your information can save lives. If you see anything we should know about, please participate in the creation of our own community avalanche advisory by submitting snow and avalanche conditions. It's okay if you leave some fields blank, just fill out what you know and/or submit photos. You can  also email us at  forecast@payetteavalanche.org.

The Friends of the Payette Avalanche Center (FPAC) needs YOU! We are in desperate need of more user support and financial assistance. The avalanche forecast is not a guaranteed service, and is in jeopardy of dwindling down to only a couple of days a week in the near future. Please help if you can by clicking the DONATE tab above. If you value this life saving information, make a donation or help the FPAC in raising funds for the future.

CURRENT CONDITIONS  Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 18 deg. F.
Max. temperature in the last 24 hours: 18 deg. F.
Average wind direction during the last 24 hours: SE
Average wind speed during the last 24 hours: 9 mph
Maximum wind gust in the last 24 hours: 16 mph
New snowfall in the last 24 hours: 1 inches
Total snow depth: inches
weather

1 to 2 inches of new snow fell overnight with light and variable winds. Today forecasts are calling for up to another 4 inches with winds out of the south southeast blowing in the 20's and gusting into the 30's.

Two-Day Mountain Weather Forecast  Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Today Tonight Monday
Weather: Snow, mainly after 11am. High near 32. East southeast wind 3 to 8 mph. Chance of precipitation is 80%. Total daytime snow accumulation of 1 to 2 inches possible. A 50 percent chance of snow before 11pm. Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 9. South southeast wind around 6 mph becoming light and variable in the evening. New snow accumulation of less than one inch possible. A 20 percent chance of snow. Mostly cloudy, with a high near 28. Northeast wind around 5 mph becoming calm in the morning.
Temperatures: High 32 deg. F. Low 9 deg. F. High 28 deg. F.
Wind direction: east southeast south southeast northeast
Wind speed: 3-8 6 becoming light and variable 5 becoming calm
Expected snowfall: 1-2 in. less than 1 in. 0 in.
Granite Mountain at 7700 feet.
  Today Tonight Monday
Weather: Snow, mainly after 11am. High near 25. Breezy, with a south wind 22 to 28 mph, with gusts as high as 38 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 2 to 4 inches possible. Snow likely before 11pm. Mostly cloudy, with a low around 14. Breezy, with a south southwest wind 15 to 20 mph decreasing to 6 to 11 mph after midnight. Chance of precipitation is 60%. New snow accumulation of less than one inch possible. A 30 percent chance of snow, mainly after 11am. Mostly cloudy, with a high near 24. East northeast wind 6 to 9 mph becoming north in the morning. New snow accumulation of less than one inch possible.
Temperatures: high 25 deg. F. low 14 deg. F. high 24 deg. F.
Wind direction: south south southwest east northeast
Wind speed: 22-28 gusting to 38 15-20 decreasing to 6-11 6-9
Expected snowfall: 2-4 in. Less than 1 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.

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