THIS AVALANCHE ADVISORY EXPIRED ON February 22, 2017 @ 6:45 am
Avalanche Advisory published on February 21, 2017 @ 6:45 am
Issued by Kent May - Payette Avalanche Center
bottom line

The avalanche danger is CONSIDERABLE above 6,000 feet. Snow and strong wind have created slabs in exposed and sheltered terrain on multiple aspects. Multiple generations of wind slabs will be sensitive to the weight of riders, may be up to 3’ thick, and have formed over a variety of surfaces.  Wind slabs are less widespread in low elevations where MODERATE danger exists due to the possibility of loose wet and wet slab avalanches.

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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With another windy day in the upper elevations wind slabs are our number one concern. Depending on location, you can find a few different generations of wind slabs that have developed over the last few days. The most suspect slopes today will be the ones with any north facing tilt due to the wind being primarily out of the south throughout this storm and again today. However, winds have been moderate to strong and quite variable so be on the lookout for clues of wind loading on all slopes in the middle and upper elevations. 

Below is weather data from Granite Mountain weather station. Pink and red are wind gusts. This station is solely funded by the PAC and through donations to FPAC and you can access this station 24 hours a day at http://payetteavalanche.org/weather-stations

Avalanche Problem 2: Storm Slab
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Brundage is reporting 11 inches of new in the last 24 hours and 22 inches in the last three days. In middle and upper elevations, where the wind has not got a chance to affect the snow or the snow was too dense (wet), storm slabs will be likely. Be heads up when traveling in/on/above or below steep terrain today. Even a small convex on a slope could cause a storm slab to be triggered. 

Today we are forecasted to get another 4-8 inches above 7,000 feet, which will cause this avalalanche problem to get worse before it gets better.

 

Avalanche Problem 3: Loose Wet
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The rain line has been fluctuating up and down over the last 24 hours. Between 6,000 and 7,000 feet where the precipitation type keeps flipping back and forth between rain and snow, be on the look out for loose wet avalanches. Below 6,000 feet where it has been (for the most part) consistent rain, the snow pack could be saturated enough to cause for a wet slab avalanche in very steep terrain. Dig down in the pack to see how deep the wet the snow is. What is the wet snow sitting on? How is it bonding?

advisory discussion

Snowmobiler/Snowbiker Travel Restrictions: Granite Mountain Area Closure is in effect Jan15-March 15, please respect Snowcats operating in this and nearby areas.  In addition there are other areas on the Payette National Forest that are CLOSED to snowmobile traffic including Jughandle Mt east of Jug Meadows,North of Boulder Mtn, East of Rapid Peak,  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 and Sergeants' 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). You can download the map to the AVENZA app on your phone, and know your exact location while you are out riding.  It is your responsiblity to know where closures exist on the forest.

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.

We rely on our snowmobiles to bring you quality forecasts. Currently two of our sleds have nearly 8,000 miles on them. We need your help raising funds for replacements! Please contact us if you can help in any way forecast@payetteavalanche.org or click DONATE tab.

recent observations

Yesterday we got a report of a natural wind slab avalanche on the Brundage ridge line just out of bounds from the ski area on a west aspect at 7,200 feet. We don't know much, however, we do know that it was approx. 200 feet wide with a crown depth of approx. 20 inches.

Sunday we had a report from local guides of natural storm slab avalanches on northwest aspects at around 7,000 feet on 'Double North'. These avalanches were failing on 38 degree slopes and ran 150 feet with a crown of approx. 1 foot. On Slab Butte the guides were able to get slabs to release 10-12 inches deep on steep roll overs with ski cuts on west aspects.

Natural avalanches are the #1 RED FLAG for dangerous avalanche conditions. 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 27 deg. F.
Max. temperature in the last 24 hours: 30 deg. F.
Average wind direction during the last 24 hours: west-southwest
Average wind speed during the last 24 hours: 8 mph
Maximum wind gust in the last 24 hours: 38 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

TODAY snow showers. Some thunder is also possible. Temperature falling to around 25 by 3pm. Windy, with a south southwest wind 32 to 38 mph, with gusts as high as 50 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 3 to 8 inches possible.

LONG TERM...Wednesday night through Monday...A pattern shift is expected Wednesday night with a deep trough forming over the Western US through the weekend. This will bring below normal temperatures to the forecast area. However, there remains above average uncertainty with the details of this pattern. A weak shortwave embedded in the upper level trough moves through the region on Thursday. Expect convectively driven snow showers with the afternoon heating on Thursday. Confidence in the forecast beyond Thursday remains low as the models continue to struggle with the evolution of a late season winter pattern. The models have been trending warmer and drier from previous forecasts and suspect this trend will continue for the next several model forecasts. A deeper low pressure system drops south along the west coast Friday night through Saturday. This system is significantly further west than previously forecast in the GFS/ECMWF/Canadian. This allows for warm southwesterly flow to return on Saturday followed by a warm frontal passage on Sunday for more widespread valley rain and mountain snow through Monday. The valley could see a mix of rain and snow early on Sunday but will switch to rain by Sunday afternoon. The upper level trough moves inland on Tuesday for a chance of rain and snow showers. Temperatures stay below normal through Saturday but increase to near normal Sunday and Monday.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Tuesday Tuesday Night Wednesday
Weather: Rain and snow showers, becoming all snow after noon. Some thunder is also possible. High near 36. South wind around 17 mph. Chance of precipitation is 80%. Little or no snow accumulation expected. Snow showers likely. Cloudy, with a low around 22. South wind 7 to 13 mph. Chance of precipitation is 60%. New snow accumulation of 1 to 2 inches possible. A 30 percent chance of snow showers. Cloudy, with a high near 32. Light west southwest wind. New snow accumulation of less than a half inch possible.
Temperatures: high 36 deg. F. low 22 deg. F. high 32 deg. F.
Wind direction: south south west-southwest
Wind speed: 17 7-13 light
Expected snowfall: less than .5 in. 1-2 in. Less than .5 in.
Granite Mountain at 7700 feet.
  Tuesday Tuesday Night Wednesday
Weather: Snow showers. Some thunder is also possible. Temperature falling to around 25 by 3pm. Windy, with a south southwest wind 32 to 38 mph, with gusts as high as 50 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 3 to 7 inches possible. Snow showers. Low around 14. Breezy, with a south southwest wind 23 to 28 mph becoming west northwest 10 to 15 mph after midnight. Winds could gust as high as 38 mph. Chance of precipitation is 80%. New snow accumulation of 3 to 5 inches possible. A 50 percent chance of snow showers. Mostly cloudy, with a high near 20. West northwest wind 3 to 6 mph. New snow accumulation of less than one inch possible.
Temperatures: falling to 25 deg. F. low 14 deg. F. high 20 deg. F.
Wind direction: south-southwest south-southwest becoming west-northwest west-northwest
Wind speed: 32-38 gusting 50 23-28 becoming 10-15 3-6
Expected snowfall: 3-7 in. 3-5 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.