Avalanche Advisory published on March 4, 2019 @ 5:20 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The Avalanche Hazard is Moderate on all upper elevation wind exposed, loaded, and cross loaded steep terrain where Human triggered avalanches are possible. The upper snow pack,  4-6 inches, or more is denser and overlying a layer of graupl that is not bonding well.  Good travel protocols like spreading out, and traveling one at a time on slopes steeper than 35 degrees. Solar aspects, especially near rocks may produce small, loose-wet point releases, and or roller balls.

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
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Very Likely
  • Size ?
    Very Large

Wind slabs can be found right now on many of our upper elevation slopes. Small, steep features near ridge tops and all leeward (down wind) steep terrain should be avoided or accessed very cautiously.  The wind slabs that we have been seeing have been failing locally, and not propagating...they are however resting on a thick layer of graupel below, and are not bonded well at all. The thickness varies from 6 inches to a foot in leeward places. This will be a layer to watch as it may produce natural avalanches in the future with additional load. 




Avalanche Problem 2: Loose Wet
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Very Likely
  • Size ?
    Very Large

Southern winds Today may help more than the Northern winds that have been helping keep the surface of the snow relatively cool. Some minor loose wet sluffing, or shedding was observed throughout the day yesterday especially near rocks, and steep South and South West aspects which are likely to pick up some additional heat today and produce  small, loose wet slides again. 

advisory discussion

PAC will issue 3 Advisories per week through the remainder of the winter as long as funding is available.  Your Observations are extremely helpful.  If you have not checked our our Observations page, it is really easy to add snow or avalanche info.  Drop down menus and prompts will lead you through it and it is easy to add photos.

Please be aware that there are areas that are CLOSED to motorized traffic in the McCall, Goose Lake and greater West Mountains area.  Just because there are tracks in some areas, does not mean they are open.  Please respect all users and closures.  See the Payette Winter Travel Maps for clarification.  Both the East and West maps can be downloaded on the Avenza app on your phone or are available at trailheads and local shops.   IT IS YOUR RESPONSIBILITY TO KNOW WHERE YOU ARE AND WHERE THESE CLOSURES EXIST. 

recent observations

Yesterday we toured the Granite Mountain area. Wind exposed terrain had a denser slab that was touched up by fresh snow on top of it and was not bonded very well at all to the snow below it. The slabs are resting on some sizable graupel which tend to fail easily but lack propagation potential.  Wind protected, lower elevation terrain showed much more stable and favorable conditions.  The Northern winds kept the surface of the snow relatively cool, as well as occasional clouds and light snow flurries. Some minor loose wet sluffing, or shedding was observed throughout the day yesterday especially near rocks, and steep South and South West aspects.

WNW Granite Mtn 6700 feet...over 11 feet of snow that is consolidating. The, denser, upper 4 inches of snow resting, and failing fairly easy on a layer of  graupel.



CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 11 deg. F.
Max. temperature in the last 24 hours: 17 deg. F.
Average wind direction during the last 24 hours: N
Average wind speed during the last 24 hours: 8 mph
Maximum wind gust in the last 24 hours: 14 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches

Area Forecast Discussion
National Weather Service Boise ID
334 AM MST Mon Mar 4 2019

.SHORT TERM...Today through Thursday...A closed low along the WA
coast will increase cloud cover over the region and introduce a
chance of showers across far southeast Oregon and southwest Idaho
today. Precipitation will be light, and chances diminish this
evening under a building ridge. The ridge axis quickly slides
eastward Tuesday, with moisture increasing in the southwest flow
on the backside of the ridge. Unsettled conditions will follow for
Wednesday and Thursday with periods of valley rain and mountain
snow bringing light to moderate rain/snow totals. Snow levels
will start between 3500-4500 feet Tuesday night lifting to
4500-5500 feet for Wednesday and Thursday. Temperatures are near
normal with Wednesday being the warmest day.

.LONG TERM...Thursday night through Sunday...A cold front will
approach southeast Oregon and southwest Idaho Thursday night into
Friday, supporting breezy northwest winds and lower the snow
levels down to valley floors for Friday. Likewise, daytime
temperatures will be several degrees cooler than previous days.
Shower coverage in the valleys will start to decrease throughout
the day on Friday, but should continue to linger over the
mountains through Saturday. Cool northwest flow will not last long
as the flow becomes southwesterly again by Sunday and Monday, and
temperatures start to rebound.


.Aviation...Generally VFR. BKN-OVC mid-level cloud cover will
limit any fog that develops. Models continue to hint at the
potential for light mountain snow showers today, which may result
in periods of mountain obscuration. Surface winds: Generally east
to southeast 5- 15 kts. Winds aloft at 10k feet MSL: Southwest to
west 15-20 kts.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: Partly sunny, with a high near 30. Calm wind. Mostly cloudy, with a low around 14. Calm wind. Partly sunny, with a high near 35. Light and variable wind.
Temperatures: 30 deg. F. 14 deg. F. 35 deg. F.
Wind direction: Calm Calm Variable
Wind speed: 0 0 Light
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: Partly sunny, with a high near 19. South southwest wind 3 to 5 mph. Mostly cloudy, with a steady temperature around 15. South southeast wind 3 to 5 mph. Partly sunny, with a high near 25. South wind 5 to 7 mph.
Temperatures: 19 deg. F. 15 deg. F. 25 deg. F.
Wind direction: SSW SSE S
Wind speed: 3-5 3-5 5-7
Expected snowfall: 0 in. 0 in. 0 in.

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.