THIS AVALANCHE ADVISORY EXPIRED ON March 17, 2020 @ 7:28 am
Avalanche Advisory published on March 16, 2020 @ 7:28 am
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard is Considerable today. New snow with gusty winds have created wind and storm slabs sitting on a variety of old snow surfaces including crusts, faceted snow and in some areas pockets of surface hoar.  Utilize safe travel protocols especially in steep terrain, and evaluate slopes before committing. Warm temperatures and the Sun will likely create loose-wet avalanches on slopes getting direct Sun.

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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Temperatures stayed warm last night, which did not give upper elevations much of a freeze. Today the Sun will be on snow that is more soft. Steep E, SE, S, SW, and W slopes are going to be under strain from solar gain as the day heats up the snow surface. Rocky outcrops are going to shed snow first. Stay on cool slopes that are not receiving direct sunlight. 

Avalanche Problem 2: Wind Slab
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Sustained gusty winds almost hit 30 mph yesterday morning, More than enough wind to move around the new light snow and form wind slabs. The wind could have deposited enough snow to form slabs up to 4 feet deep in places. The direction has varied some, and has likely formed slabs on the Northern end of the compass. It may be difficult to tell where the direction has been as most of the obvious signs like sculpting and pillows have been covered up by new snow yesterday.

Steep upper elevation slopes on all aspects should be apraoched with suspect and good travel protocols.

Avalanche Problem 3: Storm Slab
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The new snow fell on a variety of snow surfaces like slick crusts, near surface facets, fairly large surface hoar crystals, and also with large graupel on the surface. 1-2 feet deep storm slabs may be reactive, and not bonded well. Sheltered areas from the wind are going to be likely hiding places. Highly variable, one might say? Upper elevations above 7,000 feet have seen almost 2 feet of snow over the weekend. Take a moment before comitting to a new slope aspect and see how well it is bonding to the snow beneth it. 

advisory discussion

If you see or trigger avalanches, please take the time to snap a picture, note key features of the slide as well as an estimate of aspect and elevation.  Your observations help us paint a better picture of what is happening across the PAC advisory area.  You can submit an avalanche or snowpack observation at: http://payetteavalanche.org/observations click on the menu link for observations then either avalanche or snowpack.  It is SUPER easy, takes 5 minutes and can be as detailed or limited as you want.  

recent observations

Yesterday, on our ski tour North of Brundage Mountain, we observed good bonding in the new snow, and signs of wind scouring and some cornices that were easy to kick off. The new snow hid a lot of wind activity. The most notable thing to us was the progressive heat, especially under full sun which changed the snow quickly and screamed March Powder. Shady aspects are shrinking, but holding the best snow. Our test pits showed moderate bonding to the older crusts which were starting to Break down in some areas.

 

 

Just before the Sun came out at noon near the top of Sgts at 7,800 feet.

 

 As soon as the Sun lit up the trees they started to shed snow. The warmer snow below, 7,000 feet got a little sticky.

 

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 30 deg. F.
Max. temperature in the last 24 hours: 30 deg. F.
Average wind direction during the last 24 hours: S
Average wind speed during the last 24 hours: 7 mph
Maximum wind gust in the last 24 hours: 18 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

.SHORT TERM...Today through Wednesday night...At 2 AM MDT this
morning an upper low was centered off northern California 40/127
slowly drifting south. The main moisture band over our CWA has
shifted out of Idaho and into central Oregon. When the low reaches
the San Francisco Bay area tonight it will elongate east/west and
rotate its main lobe northward and into our CWA early Tuesday,
eventually forming a new low in northern Nevada Tuesday night. The
strong lobe will increase pcpn in our southern zones late tonight
and especially Tuesday and the new low will keep it going Tuesday
night into Wednesday, with pcpn Wednesday ending up in an arc across
central Idaho and eastern Oregon. The entire system will weaken and
shift east Wednesday evening ending the pcpn except along the ID/NV
border. Instability today will generate isolated afternoon and
early evening thunderstorms in Harney and Malheur Counties. The
Idaho side looks relatively stable today. Tuesday afternoon the
main instability will be in Idaho north of the Snake Basin, and
Wednesday afternoon in southwest Idaho from the Snake Basin south.
Snowfall will be minimal today and Tuesday, but will accumulate
several inches in southern Harney County Tuesday night and Wednesday
and also 1-3 inches in the Boise Mountains and west central Idaho
Mountains. Temperatures will be mild through Tuesday night under
generally southerly flow aloft, then a little cooler Wednesday.
Surface winds will be generally east or southeast 10-20 mph through
Tuesday night then northwest 5 to 15 mph Wednesday.

.LONG TERM...Thursday through Monday...The upper low center will
finally push far enough eastward Thursday night into Friday to
start drying conditions. This will be short lived, however, as
another closed low pushes south along the coast. Models are still
struggling to come to an agreement with this low, but expect showery
conditions to move back into the region by Saturday afternoon.
Temperatures will remain right around normal for this time of year.

&&

.AVIATION...Isolated showers will continue through late morning
creating MVFR/IFR conditions with mountains obscurations. Drier
conditions through early afternoon before showers move north from
Nevada. Much of the showers will remain in SE Oregon with a few
showers down in the Owyhee Mountains on the Idaho side. Surface
winds, generally north-northeast 5-10kts. Winds aloft to 10k feet
MSL, southeast 15-20kts.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: Sunny, with a high near 46. Calm wind. Mostly clear, with a low around 29. Light northeast wind. A chance of rain and snow showers after noon. Mostly sunny, with a high near 45. Calm wind. Chance of precipitation is 40%. Little or no snow accumulation expected.
Temperatures: 46 deg. F. 29 deg. F. 45 deg. F.
Wind direction: Calm NE calm
Wind speed: 0 light 0
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: Sunny, with a high near 34. Northeast wind 3 to 6 mph. Mostly clear, with a low around 25. Northeast wind 6 to 8 mph. A 50 percent chance of snow showers after noon. Mostly sunny, with a high near 33. East wind around 5 mph becoming light and variable. New snow accumulation of less than a half inch possible.
Temperatures: 34 deg. F. 25 deg. F. 50 deg. F.
Wind direction: NE NE E becoming variable
Wind speed: 3-6 6-8 light
Expected snowfall: 0 in. 0 in. less than one half 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.