THIS AVALANCHE ADVISORY EXPIRED ON February 11, 2017 @ 7:03 am
Avalanche Advisory published on February 10, 2017 @ 7:03 am
Issued by Dave Bingaman - Payette Avalanche Center
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The Avalanche Danger is HIGH throughout the West Central Mountains and surrounding areas.  High winds, above freezing temperatures, and rain falling on the snowpack up to 8000 feet over the last 24 hours have created dangerous avalanche conditions. Numerous large avalanches have been reported in both upper and lower elevation areas. High hazard will continue through the day as water continues to soak deeper into the snowpack creating the potential for large wet slab avalanches.

How to read the advisory


  • Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Avalanche Problem 1: Wet Slab
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All of our local Snotel sites recorded temperatures into the upper 30's yesterday and into the evening last night.  In addition, between 1.1 and 1.3 inches of Snow Water Equivalent was recorded through the last 24 hours. Not many folks were out in the mountains yesterday but we did get reports from the Yellowpine area that there were several large avalanches blocking roads in that area as well as a natural avalanche estimated as an R3,D2(size relative to path and destructive potential) in the Lake Fork/Lick Creek area near Slickrock.  The danger of large wet slab avalanches will continue through the day today as the free water that was added to the snowpack works it way further into the snowpack.  With the current structure of the snowpack containing multiple buried weak layers, crusts and layers of old wind slab some of these avalanches have the potential to be very large if they fail in deeply buried layers.  Predicting wet slab avalanches is hard if not nearly impossible based on the rate at which the liquid water percolates through the snowpack.  We have all the ingredients in place for some large avalanches right now.  These avalanches may impact areas that don't normally see avalanches (lower elevations), run farther in their paths, and will have large destructive potential.  Avoid avalanche terrain today, wait for the snowpack to cool off over the next few days before venturing into avalanche terrain and be aware of what is above you if you are in the mountains today.

Avalanche Problem 2: Loose Wet
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Wet loose avalanches will almost certainly be occurring again today, especially in lower elevation locations.  These avalanches may be small or large, depending on the location. When triggered even a small wet loose avalanche can pack a punch because of its mass and will quickly entrain more material as it moves down hill. The snowpack is like a melting snowcone today and travel in avalanche terrain should be avoided.  Temperatures in the valley yesterday reached into the 40's with over an inch of rain recorded. Temperatures in the upper elevations were in the mid to upper 30's. The combination of warm temperatures and high elevation rain is never good for the snowpack.  The good news is that a cooling trend will begin tonight with overnight temperatures forecasted to drop into the teens.  The long term effect of this will be a stable snowpack but it will take several days of cooling to refreeze the snowpack completely due to the insulating properties and depth of the snowpack.  The deeper the saturation zone reached into the snowpack the longer it will take to refreeze it.

advisory discussion

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

Slab avalanches were being triggered earlier this week after last week's storm.  The additional loading of the snowpack with additional snow, high winds and windloading combined with over 1 inch of rain finally pushed some areas of our snowpack over the edge.  We have ad reports of avalanches in both high and lower elevations that are getting larger.  We will be out in the mountains today to see what else happened.  Based on the amount of new snow we received last week combined with the winds and the lingering instabilities deeper in the snowpack, we have all the ingredients for some large avalanches through the day again today.

Also, if you are up high today, be aware that some very thick, dense wind slabs may be lingering near the ridgetops. Cornices have also gotten very large in the last week. With the added weight of the rain yesterday, these are going to be failing.  When they do fail you don't want to be near the edge, below or on slopes close to them, big cornices are great triggers for deeper slab avalanches. 

Please let us know if you see or trigger any avalanche activity.  A photo is literally worth a thousand words when it comes to getting the word out about avalanche conditions.  It is easy to use our observations link or send us an email.  If possible, take a picture, note your approximate elevation and which direction the slope faces.  If you want a gold star, let us know average crown height and whether the bed surface is firm or soft.  Take a look at our observations page, it has drop downs that prompt you for all kinds of info...you don't have to fill everything out.  Just let us know what you saw.  We REALLY appreciate it and the information you share may help save a life.

 

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 28 deg. F.
Max. temperature in the last 24 hours: 34 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 14 mph
Maximum wind gust in the last 24 hours: 38 mph
New snowfall in the last 24 hours: 2 inches
Total snow depth: 59 inches
weather

Cold front passing through  SW Idaho at this hour with rain showers. Front and showers will shift to south-central Idaho this morning and exit our CWA this evening. Satellite shows a flat wave on the front in southeast Oregon that may keep showers going in SW Idaho until sunrise, a little longer than progged. Upper trough along the northwest coast will move inland today with a couple more weak shower bands, but the main thing will be significant cooling tonight and Saturday. The cooling will lower the snow level and halt the snowmelt tonight through the weekend. But melting is fully underway now and additional rain will keep flood advisories and warnings and avalanche warnings going today. Winds will shift from southeast to light northwest today and continue from the northwest tonight and Saturday.

Sunday through Friday...An upper level ridge will build across the region starting Sunday afternoon. Temperatures aloft will warm, causing an inversion to develop. Expect mostly sunny skies across most of the region except for the lower Treasure Valley where stratus could develop and linger. Temperatures will be right around normal in the Upper Treasure and Magic Valleys, except well above normal in the mountains, and below normal near Ontario, OR, depending on stratus development. Temperatures around 10,000ft MSL warm to unseasonably warm values, near 36F on Wednesday afternoon. The upper level ridge begins to break down by Thursday, and unsettled conditions return with snow and freezing levels lowering to around 4,000-5,000 ft by Saturday.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Rain and snow showers, mainly before 11am Snow showers likely, mainly before 11pm A 20 percent chance of snow showers before 11am. Mostly cloudy.
Temperatures: 39 deg. F. 19 deg. F. 30 deg. F.
Wind direction: S/SW South West
Wind speed: 5-9 5-7 Calm then increasing to 6 mph in the afternoon.
Expected snowfall: in. in. in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Snow showers likely, mainly before 11am. Snow showers likely, mainly before 11pm A 20 percent chance of snow showers before 11am then mostly cloudy.
Temperatures: 29 deg. F. 15 deg. F. 22 deg. F.
Wind direction: SW SW W/NW
Wind speed: 15-22 14-16 7-11
Expected snowfall: 1-2 in. 1 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.