Avalanche Advisory published on March 13, 2019 @ 7:19 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The Avalanche Hazard is Moderate today.  Expect fresh wind slabs from gusty Northwest winds upwards of 28 MPH that are forecasted to continue through this evening. The Sun will heat up the snow today, along with a warming trend and likely produce wet-loose slides on steep solar influenced slopes. 

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

Winds have shifted overnight from the Southwest, and are now blowing out of the Northwest. There were gusts last night at the Granite weather station upwards of 28 MPH. The weather forecasters are calling for Gusty Northwest winds through this evening, so you can expect fresh wind slabs in the upper elevations up to a foot in depth in new (leeward) areas. 

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

The new 4-6 inches of snow in the last 24 hours will be  getting warmed up in todays Sun. Expect mostly shallow loose wet, point release slides on solar aspects.  South, Southwest, and West slopes will be picking up a good amount of solar heat in afternoon, and in the near future along with a rising temperature trend. Rollerballs and pinwheels are good indicators that you might need to move onto a cooler slope aspect.






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 and appreciated by all backcountry users.  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

Our deep snow pack consists of a variety of soft snow and crusts that formed from the cooling and warming that has repeated itself over the last few weeks with some layers not having bonded well, and producing natural avalanches on many East and Northeast slopes that got overloaded by the wind and Sun.  Test pits have shown improving stability, but overall makeup is not super inspiring. Solar aspects formed a crust from warm temps and the powerful March Sun that is not desirable on skis, but hardly noticeable boondocking on a sled. North aspects still hold good soft snow. 




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: 20 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: 9 mph
Maximum wind gust in the last 24 hours: 28 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches



Area Forecast Discussion
National Weather Service Boise ID
313 AM MDT Wed Mar 13 2019

.SHORT TERM...Winds have maintained advisory speeds through
the ight in the western Magic Valley, and should become even
slightly stronger during the day today. Models continue to
target Mountain Home and vicinity for the strongest winds of
all, approaching high-wind-warning thresholds. The advisory
category, however, is more representative of the overall
situation in southwest Idaho. We enlarged the advisory area
a little to take in the Owyhee Mountains, and also extended
it to end at 8 PM MDT this evening, rather than 6 PM. Today
through Thursday will be the coldest period under northerly flow
aloft. Scattered snow showers in the mountains will end this
evening, then dry after that as the area comes under the influence
of high pressure aloft building in from the Pacific. Thursday
night and Friday be a little warmer and much less windy. Models
show a weak wave coming inland through the main upper ridge at
that time with some cloudiness, especially on the Oregon side.
Sunday night through Tuesday night...Clear to partly cloudy skies
with varying upper level winds are the expected conditions
throughout the region. Showery conditions are expected briefly along
the Central Idaho Mountains as a trough brushes by at the onset.
However, by Monday afternoon, look for clearing and breezy upper
level winds (from the east) to set up as a drier, high pressure
system moves down from the north. High temperatures are expected to
measure in around 10 degrees above normal while lows drop down to
near normal.

.LONG TERM...Saturday through Wednesday. Models continue to show a
dry extended under a broad ridge over the Western US coast. A
weakening trough may ride up and and over the ridge during the
weekend, but it will bring little more than cloud cover to the CWA.
There is little confidence in the breakdown of the ridge next week,
and models continue to differ on it. Nonetheless, the extended will
likely see a warming trend with a few degrees increase to
temperatures each day.


.AVIATION...Generally VFR. Windy and dry. Surface winds: northwest
15-25kt, increasing to 20-30kt during Wed afternoon with higher
gusts near KBOI KMUO KTWF KJER. Winds all calm down just after
sunset, and return to 10 kts or less. Winds aloft at 10kft MSL: N-NW

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Wednesday Wednesday Night Thursday
Weather: Isolated snow showers before noon. Partly sunny, with a high near 33. Breezy, with a light northwest wind becoming north northwest 15 to 20 mph in the afternoon. Chance of precipitation is 20%. Mostly clear, with a low around 8. Northwest wind 8 to 13 mph becoming light north in the evening. Sunny, with a high near 35. Calm wind.
Temperatures: 33 deg. F. 8 deg. F. 33 deg. F.
Wind direction: NNW NW Calm
Wind speed: 15-20 8-13 becoming light 0
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: Scattered snow showers before noon. Partly sunny, with a high near 21. Wind chill values between zero and 6. North northwest wind 7 to 17 mph. Chance of precipitation is 40%. Total daytime snow accumulation of less than a half inch possible. Mostly clear, with a low around 8. North wind 6 to 9 mph. Sunny, with a high near 26. North wind around 6 mph becoming calm in the afternoon.
Temperatures: 21 deg. F. 8 deg. F. 26 deg. F.
Wind direction: NNW N N
Wind speed: 7-17 6-9 6
Expected snowfall: Less than one half 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.