THIS AVALANCHE ADVISORY EXPIRED ON March 9, 2017 @ 6:58 am
Avalanche Advisory published on March 8, 2017 @ 6:58 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The avalanche danger is CONSIDERABLE today at all elevations due to natural avalanches being possible, and human triggered avalanches being likely. New, heavier snow, moderate winds, and warming temperatures will cause the avalanche danger to rise this evening, especially at elevations between 5,000 and 6,000 feet where rain on snow is forecasted.

 

How to read the advisory


  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Storm Slab
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The Brundage mountain webcam is showing 8 inches of new snow this morning. This new snow is warmer and heavier, and has now created an upside down snowpack. The surface will be much denser than the older snow beneath it, making for difficult skiing and riding conditions. Human triggered avalanches will be likely as we now have a classic bad recipe of a strong layer over a weak layer.

 

 

Avalanche Problem 2: Loose Wet
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Temperatures are already 10-12 degrees higher than yesterday. As the temperatures rise this afternoon, rain is forecasted to fall up to 6,000 feet which will increase the possibility of natural, loose-wet avalanches. Human triggered wet-loose avalanches will be likely in the lower elevations.

Avalanche Problem 3: Wind Slab
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Winds have primarily out of the West, Southwest over the last 24 hours which have been doing a fair job of loading Northern aspects, creating wind slabs.  Terrain features help to create swirl and thus cross-load, and load various aspects, not just the Northern aspects.

Photo of wind shallow slab sensitivity on East aspect of Slab Butte Yesterday near 8,000 feet

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 responsiblity 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").

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.We have equipment that is overdue for replacement but lack the funds to purchase new gear including weather station parts and our forecast sleds.  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

Yesterday, on Slab Butte we observed significant cornice growth, and kicked off sizable pieces of overhanging cornices with our skis on the East ridge around 8,000 feet. We were also able to get some cracking in the shallow wind slabs on the ridge just to the South of the Face.

If you see or trigger an avalanche please let us know. These observations are crucial to our forecasts. You can send us an email at: forecast@payetteavalanche.org or better yet take 5 minutes and submit your observations through our website. Photos, aspect, elevation, trigger type and depth will help us get the word out and may save a life.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 24 deg. F.
Max. temperature in the last 24 hours: 24 deg. F.
Average wind direction during the last 24 hours: W
Average wind speed during the last 24 hours: 7 mph
Maximum wind gust in the last 24 hours: 20 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

SHORT TERM...Today through Thursday...Strong, moist, westerly
flow aloft will continue over the area through Thursday. Precip
will continue over the mountains, especially west facing slopes,
throughout the period. A slight increase in moisture Wednesday
night and early Thursday will help to overcome mountain downslope
effects, and thus the precip chances for valley locations are
highest during this period. Snow levels will continue to rise
slowly, from about 5000-6000 ft MSL today, to 6000-7000 ft MSL on
Thursday. Surface temperatures will be 5 to 10 degrees above
normal. Snowmelt will continue to be of the most concern, see
Hydrology section below.

.LONG TERM...Thursday night through Wednesday...A system moving
through Friday brings ample moisture and precipitation to the West
Central and Boise Mountains. Snow levels sit right around 7000 feet
MSL on this day so most of the precipitation will fall as rain.
Heavy runoff and melting snow means concerns for flooding potential.
Ridging builds back into the area by Saturday morning with
temperatures climbing into the upper 50`s for valley locations.
Things remain dry until Sunday when disturbances begin to pass
through the flow. Most of the precipitation stays in the northern
portions of the CWA. Slight chances of precipitation remain for
extreme northern zones through Tuesday morning. Models are in
disagreement on timing of a disturbance towards the end of the
period. The ECMWF wants to bring in a small wave Tuesday while the
GFS holds off until Wednesday. Temperatures remain above normal for
this time of year throughout the period with some models suggesting
highs in the low 60`s for valley locations by the end of the
period.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow before 11am, then rain and snow. High near 37. South southwest wind 9 to 11 mph. Chance of precipitation is 90%. New snow accumulation of less than one inch possible. Rain. Low around 32. South wind 8 to 10 mph. Chance of precipitation is 90%. Rain. High near 40. South wind around 8 mph. Chance of precipitation is 100%.
Temperatures: high 37 deg. F. low 32 deg. F. high 40 deg. F.
Wind direction: SSW S S
Wind speed: 9-11 8-10 8
Expected snowfall: less than one in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow. High near 29. Breezy, with a south southwest wind 16 to 20 mph. Chance of precipitation is 100%. New snow accumulation of 3 to 5 inches possible. Snow. Low around 26. Breezy, with a southwest wind 15 to 21 mph. Chance of precipitation is 100%. New snow accumulation of 3 to 5 inches possible. Snow. High near 34. South southwest wind 11 to 14 mph. Chance of precipitation is 100%. New snow accumulation of 3 to 5 inches possible.
Temperatures: high 29 deg. F. low 26 deg. F. high 34 deg. F.
Wind direction: SSW SW SSW
Wind speed: 16-20 15-21 11-14
Expected snowfall: 3-5 in. 3-5 in. 3-5 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.