THIS AVALANCHE ADVISORY EXPIRED ON February 12, 2017 @ 7:33 am
Avalanche Advisory published on February 11, 2017 @ 7:33 am
Issued by Dave Bingaman - Payette Avalanche Center
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The Avalanche Danger is Considerable today above 7000 feet where new windslabs formed through Thursday night and Friday on leeward slopes.  Below 7000 feet the Danger is Moderate.  Falling temperatures yesterday afternoon and last night have already begun re-freezing our very soggy snowpack.  The possibility of human caused wet loose or wet slab avalanches will remain until the snowpack has completely refrozen.  Avoid steep slopes until the lower snowpack refreezes.

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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Our Avalanche problems have flip flopped over the last few days quite a bit but wind seems to be the constant factor in our snowpack this year.  We found quite a few newly deposited wind slabs in mostly Northerly terrain yesterday but also saw evidence of loading and crossloading on E and W aspects as well. The areas that we inspected  held shallow but brittle wind slab mostly on the highest ridgelines where there was enough new snow to begin forming them after the rainline crept up to over 8000ft. on Thursday.  After the amount of wet avalanches that occurred during the storm, thin wind slabs seem like a relatively easy problem to manage.  You are going to see a lot of avalanche debris if you are in the mountains today, as always, please send us your pictures or observations.

 

 

 

 

Avalanche Problem 2: Loose Wet
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Our snowpack received a serious soaking over the last few days.  Rain began Wednesday evening in the valley and the rainline rose to over 8000ft during the day on Thursday.  Creeks raged, numerous natural wet loose slides occurred as well as a few large wet slabs.  We covered a lot of ground yesterday and saw quite a few decent sized avalanches. We also found that the rain had saturated the snowpack over 3.5 feet down as nearly 2.5 inches of rain fell.  In the upper elevations, there was already a supportable crust forming by mid afternoon.  As the cold front cooled things down, the snowpack near 6500 feet was already forming a thin crust as well.  Overnight temperatures dropped into the low teens and will have done a great job setting things up.  If you are headed out today, bear in mind that it is still going to take a few days for the rest of the snowpack to refreeze.  Avoid steep terrain especially if the snow surface feels punchy or you can penetrate through the surface crust. By tomorrow, our wet loose/slab instabilities will probably be gone.  Day time warming is going to be the next weather factor to keep in mind. Temperatures during the day will be warming tomorrow through the early part of the week creating the potential for loose wet slides as temperatures climb.

 

Sawtooth Pk wet loose avalanche from 2/10/17. This was substantial enough to break small trees.  More than enough material was entrained to bury a person or car.

advisory discussion

Warren Wagon snowmobile route is Closed right now.  A creek between Fisher Creek and Deep Creek flash flooded/experienced a debris flow that has blocked the road with snow and woody debris as well as cutting a deep channel through the snowmobile route and is impassible.  Acess to the Copet Creek Route is still open.  The Brush Creek route is now open and should be groomed tonight.  Lick Creek Road had water flowing across it yesterday afternoon as well near the Forest Boundary.

Snowmobiler/Snowbiker Travel Restrictions:  a quick reminder that the Granite Mountain Area Closure is now in effect, 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, 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.

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.

recent observations

 See our avalanche observations for pics from some of the slides we found yesterday.  Yesterday conditions were better than we expected, the snow was beginning to cool but soft enough to maintain a sidehill on snowmobiles.  If you are out today you better have scratchers for the road riding, trails are rough and they are going to be firm today.  

This temp profile from our Granite weather station tells all, the temp line is following the dewpoint line from above freezing to near 10 degrees at 7700 feet:

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 13 deg. F.
Max. temperature in the last 24 hours: 30 deg. F.
Average wind direction during the last 24 hours: W/SW
Average wind speed during the last 24 hours: 6 mph
Maximum wind gust in the last 24 hours: 18 mph
New snowfall in the last 24 hours: 4.5 inches
Total snow depth: 65 inches
weather

Colder and drier today through Sunday under northwest flow aloft behind exiting upper trough. Still enough clouds and moisture for a few snow showers in northern mountains today. Mostly clear tonight and Sunday excpt patchy fog in northern valleys and in Lower Treasure Valley. Light northwest winds today except moderate in south-central Idaho. Light and variable winds tonight, then light southeast Sunday. Snow level will be near valley floors through Sunday generally stopping snowmelt for the weekend. Temperature inversion will form in the Lower Treasure Valley with Sunday`s highs about 3 degs lower than today. Elsewhere, high temps Sunday will be much like today.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Saturday Saturday Night Sunday
Weather: Isolated snow showers before 11am. Mostly sunny. Mostly clear Mostly sunny
Temperatures: 31 deg. F. 6 deg. F. 30 deg. F.
Wind direction: NNW WNW Calm
Wind speed: Around 5 Around 5 Calm
Expected snowfall: Trace in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Saturday Saturday Night Sunday
Weather: Isolated snow showers before 11am. Partly sunny Partly cloudy, with a low around 13. Wind chill values between -1 and 9 Mostly sunny
Temperatures: 22 deg. F. 13 deg. F. 31 deg. F.
Wind direction: NW SW WSW
Wind speed: 5-14 8-13 7-15
Expected snowfall: Trace in. 0 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.