THIS AVALANCHE ADVISORY EXPIRED ON March 20, 2017 @ 6:16 am
Avalanche Advisory published on March 19, 2017 @ 6:16 am
Issued by Dave Bingaman - Payette Avalanche Center
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The Avalanche Danger is Considerable  today at all elevations/aspects.  Loose, wet avalanches will be your main concern today,  but upper elevation lee slopes are now sporting a fresh crop of wind slabs resting on a variety of firm surfaces below.  Expect them on primarily E through NW slopes.  Cornice failures are also a major concern,  cornices are large and overhanging ridgelines much farther than you might expect.  Avoid travelling near the edges of and spending time below these monsters.

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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Warm weather and rain are continuing to degrade our snowpack.  Temperatures at local Snotel sites and at the 7600 ft Granite weather station are above freezing again this morning.  Local Snotel Sites have lost between 30 and 40 inches of their snow pack in the last 10 days as a result of the wet, warm weather.   With the lack of freezing temperatures, especially below 7,500 feet, you run a good chance of starting a loose wet avalanche in steep terrain. Rain showers and periods of heavier rain today will increase the potential for natural and human caused wet slides through the day, a cool down tonight will help but temperatures will be above average for the next few days as another round of moisture enters the area.

Avalanche Problem 2: Wind Slab
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Winds have been whipping up high for the last few days.  While not a lot of snow has been available for transport, a few inches of upper elevation snow fell Thursday and again last night.  We found shallow wind slabs to be fairly widespread near the ridges on Friday and have added a few additional inches of snow with 30 mph wind gusts to create some thicker slabs today.  Many of these wind slabs are resting on firm snow below whether rain, heat or wind crusts, there is some very firm snow below the new snow in the upper elevations.  Most of these slabs will found on E, NE, N and NW facing slopes.  Rain followed by cooler temperatures tonight will help these consolidate quickly but they are likely going to be more reactive if the snowline climbs today or tomorrow.

Avalanche Problem 3: Cornice
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Many of the ridgelines in the area are still sporting some very large, overhanging cornices.  We had a report of a large, human triggered cornice failure earlier this week and also have seen many areas where large sections of cornice have already succumbed to the pull of gravity.  Cornice failures are very common in the spring and we have a bumper crop of monster cornices this year.  Rain at or above 7000 feet today and tomorrow will increase the likelihood of cornice failures and natural avalanches below when they fall. Avoid travel on or near large cornices and stay off slopes that have large, overhanging cornices above them.  Make sure you are aware of where the snow begins and the actual ridgelines end,  don't venture out past the last trees and rocks that mark the edge of terra firma. Notice how far the cornices in the photos below are extending beyond the ridges.

      

advisory discussion

Snowmobiler/Snowbiker Travel Restrictions: 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.  It is your responsibility to know where closures exist on the forest.

The Granite Mountain Area Closure is in effect Jan15-March 31, please respect Snowcats operating, signed and unsigned closures and other users 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, North of Boulder Mtn, East of Rapid Peak, North of the 20 mile drainage, 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").  

Ski areas are closed to snowmobile traffic, last week a group of snowmobilers poached the Northern portion of Tamarack Resort crossing under a fixed and signed rope line and left trenches on 3 of the ski runs that don't get groomed. Don't be "that guy" that gives sledders a bad name, please respect boundaries, snowmobiling at a ski resort is a low blow and a safety concern.

recent observations

No new avalanches were reported or observed, wet weather has put a damper on winter recreation this weekend but if you are out and see avalanche activity, please let us know what you see.  Local snotel sites have reported about .5 inches of rain last night and the forecast is calling for another .5 to .75 inches today, so expect another day with soggy weather in the mountains and rain/snowlines close to 7200 feet today and closer to 8000 feet tomorrow.

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: 41 deg. F.
Average wind direction during the last 24 hours: WSW
Average wind speed during the last 24 hours: 12 mph
Maximum wind gust in the last 24 hours: 35 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

SHORT TERM...Today through Monday...Moist southwest flow will
continue through the short term, even as a weak ridge axis moves
through late tonight. A cold front is located roughly from Adams
County southwest to southeast Baker County to near Burns.
Showers, and possibly thunderstorms in the afternoon and early
evening, will continue over the area. QPF totals in the short term
range from around a tenth of an inch in the lower elevations of
the Snake River Plain, to between a quarter and three-quarters of
an inch in the mountains. As this rain falls on already saturated
soil, further flooding problems are likely. See the hydrology
section below for a discussion of those factors. Temps will remain
above normal despite the cloud cover and precipitation due to the
warm air advection associated with the southwest flow aloft. The
best chance for thunderstorms appears to be Monday after the weak
ridge axis moves north.

LONG TERM...Monday night through Saturday...Two successive upper
level troughs through the long term will keep the area in an
active pattern. The CWA will remain in the warm sector of the
first on Monday night through early Tuesday, before a cold front
moves through. Models continue to show Tuesday being a day for
widespread showers and isolated thunderstorms with snow levels
7000-8000 ft then gradually lowering to 5000-6000 by Wednesday
morning. A brief break in showers is expected on Wednesday
morning, but a shortwave moving through the flow will be enough to
spark more showers and possibly thunderstorms Wednesday
afternoon. By Thursday the upper level axis will be off to the
east, and a brief reprieve from precipitation will give way to the
next upper low moving into the PACNW on Friday. Model agreement
continues to be relatively good for this system to impact the area
during next weekend. Temperatures remain right at or above normal
through the period.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Sunday Sunday Night Monday
Weather: Showers, with thunderstorms also possible after noon. High near 44. South wind 3 to 5 mph. Chance of precipitation is 90%. A chance of showers and thunderstorms before midnight, then a slight chance of showers. Cloudy, with a low around 34. East wind 3 to 5 mph. Chance of precipitation is 30% Showers, with thunderstorms also possible after noon. High near 47. South wind 5 to 8 mph. Chance of precipitation is 90%.
Temperatures: 44 deg. F. 34 deg. F. 47 deg. F.
Wind direction: S E S
Wind speed: 3-5 3-5 5-8
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Sunday Sunday Night Monday
Weather: Snow showers. Some thunder is also possible. High near 37. South southwest wind around 8 mph. Chance of precipitation is 80%. New snow accumulation of around an inch possible. A 40 percent chance of snow showers. Some thunder is also possible. Cloudy, with a low around 29. South wind around 8 mph. Little or no snow accumulation expected Snow showers. Some thunder is also possible. High near 40. South wind 9 to 14 mph. Chance of precipitation is 90%. New snow accumulation of less than a half inch possible.
Temperatures: 37 deg. F. 29 deg. F. 40 deg. F.
Wind direction: SSW S S
Wind speed: Around 8 Around 8 9-14
Expected snowfall: 1 in. 0 in. Trace 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.