THIS AVALANCHE ADVISORY EXPIRED ON January 10, 2019 @ 7:07 am
Avalanche Advisory published on January 9, 2019 @ 7:07 am
Issued by George Halcom - Payette Avalanche Center
bottom line

Considerable Avalanche hazard exists throughout the West Central Mountains.  Fresh wind Slabs have formed and will be likely in the upper elevations, and wet slides may be possible from a warming trend and forecasted rain in the lower elevations. More snow and moderate wind is forecasted today and tonight above 5-6,000 feet.

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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Gusty winds have been the theme for weeks. Yesterday, we observed many of the peaks shooting huge plumes of snow from the Southern winds into Northern aspects. Wind slabs recently have formed above a large layer of graupel, and were failing on isolation in the upper foot in mit pits on West aspects. 

Today, more wind and snow may produce natural avalnches, or linger waiting for a human trigger?

Travel safe. Wind loaded terrain should be approached with cation, if not avoided  today!

 

Avalanche Problem 2: Wet Slab
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Today the lower elevations of the advisory area, 5-6,000 feet, are forecasted to get rain on the snow pack. Rain on snow will likely make steep rocky areas peel loose wet, and maybe even a wet slab...hopefully the weather forecasters are wrong, and it cools off, but the temperatures are much warmer the past 24 hours.

Avalanche Problem 3: Persistent Slab
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Over the last week, we have observed our basal snow pack (near the ground) gaining a lot of strength. We still would like to monitor this weak layer and gain some more confidence in its stability, as the distribution has been highly variable across the advisory area. The faceted snow that was dry and sugary has been warmed by mother nature, and is on its way to becoming a great base when it cools. Right now we are able to make a wet snowball with it. 

The variability in our advisory area is going to keep this problem on our radar in the next couple weeks, especially in areas where the snow pack is still thin enough for a sledder or skier to affect them.

Cautious travel is advised, the weak layers that continue to get deeper in our snow pack are getting better, but guess what? They are still weaker than most of the snow above them. 

advisory discussion

Due to the partial government shutdown, avalanche forecasting will be limited.  We expect to forecast 3 times a week until the shutdown has ended.

Join FPAC and PAC forecasters for a benefit and social at Broken Horn Brewing on January 10 at 6PM.  $1 of every pint sold goes to the FPAC.

Your observations are very helpful to the PAC staff and help create a better picture of the complex terrain in our advisory area.  You can click on the add observations linkand add as little or as much detail as you have.  It is easy to navigate and will also upload pictures easily.  Please contribute to your local forecast by sharing what you see or experience even if it is just good snow. or a trip report.

recent observations

Yesterday, near Secesh Summit, Deep Lake we observed a wind effected snowpack with some nicer soft snow on top of it. The wind packed layer was sitting on some graupel which was not bonded well at the time. I was able to get some cracking in the punchy wind pack above the skin track on a west aspect near 7,000 feet, but not much propigation with the light new snow on top of it. 

Check out our obervations page for the pit profile, or to submit an observation of your own. By the way the skiing and riding was still good, and covergae is getting better in the mountains!

 

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 32 deg. F.
Max. temperature in the last 24 hours: 32 deg. F.
Average wind direction during the last 24 hours: SE
Average wind speed during the last 24 hours: 11 mph
Maximum wind gust in the last 24 hours: 36 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

 

Area Forecast Discussion
National Weather Service Boise ID
317 AM MST Wed Jan 9 2019

.SHORT TERM...Today through Friday...The broad trough of low
pressure continues to slowly slide eastward into the western US
this morning. Southeastern Oregon and southwest Idaho are
currently under the eastern periphery of the trough, with broad
southwesterly flow in place aloft along with a swath of mid/upper
level moisture. Plenty of clouds are showing up on satellite,
along with pockets of precipitation over the central Idaho
mountains. Strong precipitation shadowing is evident downstream of
the Sierra Nevada mountains limiting any significant accumulations
over the area. The pressure gradient remains strong, with east to
southeast winds exceeding 20 mph across portions of the upper
Treasure Valley and Magic Valley in Idaho.

The trough is expected to move overhead during the next 24 hours
with the axis passing over our area overnight tonight into early
Thursday. Precipitation chances will favor the higher terrain of
Oregon and Idaho, and overall accumulation is going to be light.
Snow levels will rise to above 5000 feet today, with above normal
temperatures anticipated for most locations. A ridge of high
pressure is expected to amplify northward over the northern
Rockies late Thursday into Friday with drying conditions, and
cooling temperatures. Morning low temperatures Friday will likely
dip below normal in most locations.

.LONG TERM...Friday night through Monday...
A dry, amplified ridge will become closed off over the northwestern
U.S. by this weekend. Valley inversions will continue to strengthen,
especially sheltered locations with snow on the ground. These areas
include the Camas Prairie and the Long Valley in southwest Idaho,
and the Burns vicinity in southeast Oregon. Daytime temperatures in
the valleys will also trend cooler each day under poor mixing
conditions. Current forecast confidence remains low on the formation
of overnight freezing fog, but will be a consideration as the
pattern gets closer.

.Monday night through Wednesday night... An active pattern
change is coming up. Breezy and showery conditions are expected
across most of the area as a series of troughs roll across the
region. Low snow levels will remain fairly persistent with a
slight increase by the end of the period, expect widespread
snowfall to predominate. Shower intensity and coverage should
increase by Wednesday with the passage of a stronger, more
organized upper level disturbance. Breezy winds should intensify a
notch in conjunction with with this stronger system. High and low
temperatures are expected to measure in around 3 to 5 degrees
above normal.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Wednesday Wednesday Night Thursday
Weather: Rain and snow likely. Cloudy, with a high near 36. South wind around 6 mph. Chance of precipitation is 70%. Little or no snow accumulation expected. Rain and snow likely. Cloudy, with a low around 29. South wind 3 to 5 mph. Chance of precipitation is 70%. New snow accumulation of less than a half inch possible. Rain and snow likely, mainly before 11am. Cloudy, with a high near 35. Calm wind. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.
Temperatures: 36 deg. F. 29 deg. F. 35 deg. F.
Wind direction: S S
Wind speed: 6 3-5 Calm
Expected snowfall: 0 plus in. Less than one half in. Less than one half in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow. High near 28. South wind around 15 mph. Chance of precipitation is 80%. Total daytime snow accumulation of 1 to 2 inches possible. Snow. Low around 24. South wind 10 to 13 mph. Chance of precipitation is 80%. New snow accumulation of 3 to 5 inches possible. Snow likely, mainly before 11am. Mostly cloudy, with a high near 26. South wind 6 to 8 mph. Chance of precipitation is 70%. New snow accumulation of less than one inch possible.
Temperatures: 28 deg. F. 24 deg. F. 26 deg. F.
Wind direction: S S S
Wind speed: 15 10-13 6-8
Expected snowfall: 1-2 in. 3-5 in. Less than one 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.