THIS AVALANCHE ADVISORY EXPIRED ON January 25, 2019 @ 7:04 am
Avalanche Advisory published on January 24, 2019 @ 7:04 am
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard is Moderate today.  Human triggered avalanches are possible in wind loaded terrain. Wind slabs that formed early this week are not bonded well and are resting on a variety of old snow surfaces, and may be hidden under newer lighter snow.  Loose, Dry human triggered avalanches are possible in steep terrain within the new snow.

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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The winds are letting up for a few days, but be on the lookout for wind slabs on all aspects in exposed terrain. The winds have been gusting from all directions. Natural Wind slab avalanches were observed on Sunday. While the posibility of natural avalanches is gone, you could kick loose good bit of snow on steep terrain, as many of the wind slabs that were formed earlier in the week are sitting below fresh light powder in places, and are not bonded at all to the older snow surfaces. 

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.

Avalanche Problem 2: Loose Dry
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The last couple of days the snow has been dry and light just like we dream about. The upper foot of the snow pack is loose, and has the potential to sluff, or run with you in steep terrain. Keep the loose dry avalanche problem in your mind as it may put you into consequential terrain.

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

This past weekend's snowstorm came in heavy and wet with a lot of wind that formed shallow wind slabs on all aspects that still show poor bonding to no bond at all, and created Natural avalanches. Monday-Wednesday temperatures cooled, and around 10-12 inches of light dry snow sits on the surface now. Skiing and riding conditions are good.

Other areas around the country, like the Sawtooth's, are seeing some big avalanches Natural, and Human triggered some 17' deep. Stability is not as good as we have seen. Our basal facets got warm, and so did our buried surface hoar, but the structure is still there. Yesterday, near Twin Lakes on a North aspect, 7700 feet, just above the Lake, we dug a pit and uncovered an old layer of buried surface hoar (that was visible to the naked eye) just over 3 feet down that failed after hard pounding on the shovel. Under a lens, the surface hoar feathers are around 4mm and are rounded/melted.  In our pits, the shallow wind slabs were failing moderately in compression, but lacked propigation.

 

 

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 19 deg. F.
Max. temperature in the last 24 hours: 14 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: 8 mph
Maximum wind gust in the last 24 hours: 32 mph
New snowfall in the last 24 hours: 2 inches
Total snow depth: 64 inches
weather

 

Area Forecast Discussion
National Weather Service Boise ID
317 AM MST Thu Jan 24 2019

.SHORT TERM...Today through Friday...A high-amplitude ridge off
the west coast will maintain a dry northwest flow aloft over
southeast Oregon and southwest Idaho through the end of the week.
Light winds, decreasing clouds and a strengthening inversion will
lead to patchy valley fog during the overnight and morning hours.
Temperatures will be around 5 degrees above normal.

.LONG TERM...Saturday night through Wednesday...Upper level ridge
will remain along the West Coast through the extended period.
Expect dry conditions and temperatures around 5 degrees above
normal. Fog and stratus may develop underneath the inversion, but
left it out of the forecast with the lack of snow cover across
much of the lower elevations. A cold front will move into MT on
Sunday night into Monday, with temperatures lowering to near
normal. Snow showers should generally stay east of the Salmon
River with this system. Otherwise, upper level ridge remains in
control through at least Thursday.

&&

.AVIATION...Generally VFR. Areas of low clouds and fog with
mountain obscuration. Surface winds: variable 10kt, except W-NW
5-15kt near MUO JER TWF during the afternoon. Winds aloft at 10kft
MSL: NW 20-30kt.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Thursday Thursday Night Friday
Weather: Patchy fog before 11am. Otherwise, mostly sunny, with a high near 32. Calm wind. Patchy fog after 11pm. Otherwise, partly cloudy, with a low around 19. Calm wind. Patchy fog before 11am. Otherwise, mostly sunny, with a high near 33. Calm wind.
Temperatures: 32 deg. F. 19 deg. F. 33 deg. F.
Wind direction: Calm Calm Calm
Wind speed: Calm Calm Calm
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Thursday Thursday Night Friday
Weather: Mostly sunny, with a high near 24. North northwest wind 5 to 7 mph becoming west in the afternoon. Partly cloudy, with a low around 16. South southwest wind 3 to 5 mph. Mostly sunny, with a high near 25. South southwest wind around 7 mph becoming north northwest in the afternoon.
Temperatures: 24 deg. F. 16 deg. F. 25 deg. F.
Wind direction: NW becoming West SSW SW becoming NNW
Wind speed: 5-7 3-5 7
Expected snowfall: 0 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.