THIS AVALANCHE ADVISORY EXPIRED ON January 21, 2019 @ 9:33 pm
Avalanche Advisory published on January 20, 2019 @ 9:33 pm
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard is Considerable today.  Natural avalanches are possible on steep solar aspects. Over a foot of snow and strong winds over the weekend have created fresh wind slabs that are resting on a variety of old snow surfaces.  Storm slabs will also be likely where new snow has not bonded to the older snow below.    

How to read the advisory


  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Loose Wet
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The Sun may poke its head out tomorrow if you are lucky. Watch out for loose wet snow sliding and peeling off solar aspects. With all of the new snow, and the first solar influence, we will likely see some rollerballs, especially near rocks.  Stay clear of steep slopes that are getting direct Sun.

Avalanche Problem 2: Storm Slab
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The latest round of snow came in heavy and wet. Areas that were sheltered from the wind may be harboring denser new snow that has not bonded yet. The new snow will need time, maybe a few days or more, to bond to some of the older snow surfaces. Storm slabs may still be sensitive to the weight of a person. Use safe protocols in steep terrain.

Avalanche Problem 3: Wind Slab
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Look for wind slabs on all aspects. The winds have been gusting out of the South loading Northern aspects with over a foot of  new snow. Natural Wind slab avalanches were observed in the Lick Creek drainage Sunday. Check out the observations for more. Today, the winds will be out of the North, loading and creating fresh new wind slabs.

Cross loading occurred also, putting fresh wind slabs in strange places that might suprise you on a variety of aspects and are resting on a variety of old snow surfaces including crusts and other firm layers.  Visibility should improve today. You should be able to see areas where the wind has sculpted the snow.  Areas with pillows, drifts or textured snow are indicators of wind loading.

Your best and safest bet today is to avoid wind loaded terrain that is steep enough to slide.  You will find better skiing and riding conditions and are less likely to trigger avalanches in areas that have been protected from the winds.

 

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.

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 link and 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

Sunday, Skiers reported a few Natural avalanches and some heavy wind loading during the day. The snow came in heavy and wet. Check out some of the observations submitted over the weekend here.

 

 

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

Area Forecast Discussion
National Weather Service Boise ID
831 PM MST Sun Jan 20 2019

.DISCUSSION...Showers continue to move through the forecast area
this evening, with lightning observed north of Boise earlier.
Forecast generally on track with activity found through the
afternoon hours, especially impacting the ID/NV border. Made a few
tweaks to change some areas after midnight to a rain/snow mention
instead of just rain...mainly impacting the Western Magic Valley.
Models continue to indicate increasing wind Monday afternoon,
especially south and east of Boise in the Treasure and Magic
Valleys. All hazards remain unchanged.

&&

.AVIATION...Mountains obscured. Areas of MVFR and IFR across
higher terrain of southwest Idaho to include the Magic Valley.
Conditions improving across southeast Oregon, north of KBNO-KONO
line and in the Snake Plain west of KTWF/KJER. Will see VFR most
areas after 18Z/Monday. Surface winds NW 5-15kts tonight, but
ramping up to 20-30 kts on Monday with gusts to 40kts. Winds aloft
at 10k feet MSL: northwest 10-20 kts through 12Z/Mon increasing to
40-50 kts after 12z/Mon.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Sunday Sunday Night Monday
Weather: A 30 percent chance of snow showers, mainly before 11am. Partly sunny, with a high near 32. North northwest wind 6 to 11 mph. Little or no snow accumulation expected. Partly cloudy, with a low around 8. North northwest wind around 6 mph becoming calm in the evening. A 20 percent chance of snow after 11am. Mostly cloudy, with a high near 25. Calm wind.
Temperatures: 32 deg. F. 8 deg. F. 25 deg. F.
Wind direction: NNW NNW Calm
Wind speed: 6-11 6 to calm 0
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Sunday Sunday Night Monday
Weather: A 40 percent chance of snow showers. Partly sunny, with a high near 17. Wind chill values between -1 and 4. North wind 13 to 16 mph. New snow accumulation of less than a half inch possible. Partly cloudy, with a low around 8. Wind chill values between -2 and 3. North wind 6 to 11 mph. A 30 percent chance of snow after 11am. Mostly cloudy, with a high near 19. Wind chill values between -1 and 9. Southwest wind 5 to 7 mph. New snow accumulation of less than a half inch possible.
Temperatures: 17 deg. F. 8 deg. F. 5-7 deg. F.
Wind direction: N N SW
Wind speed: 13-16 6-11 7
Expected snowfall: Less than one half in. 0 in. Less than one half 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.