THIS AVALANCHE ADVISORY EXPIRED ON February 25, 2020 @ 7:09 am
Avalanche Advisory published on February 24, 2020 @ 7:09 am
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard today is Moderate above 7,000 feet on wind loaded slopes steeper than 30 degrees.  Gusty winds upwards of 36mph have created wind slabs on multiple upper elevation slopes that may be sensitive to the weight of a skier or snowmobiler.  

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
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  • Likelihood ?
    Certain
    Very Likely
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  • Size ?
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Winds picked up during the onset of yesterdays teaser storm that put down a few inches near the Granite Mtn weather station. Above is a graph showing hours of gusts above 20 mph, and some hitting 36mph. Fresh, sensitive wind slabs from 6-12 inches in depth are possible in leeward terrain.

Some of the slabs may have formed on crusts that formed from the Sun. Expect poor bonding of the new snow, especially on slopes tipped towards the Sun. Local terrain is going to dictate loading and cross-loading patterns. Watch for changes in the density of the snow surface as you travel and obvious visual clues like ripples, drifts or partially covered old tracks to help identify potential wind slab or wind loaded slopes.  

Cornices are also getting large and are overhanging quite a bit in some areas.  Avoid traveling near the edges of corniced ridge lines.  Big cornices are unpredictable and can break further back than you expect.

 

 

 

 

 

advisory discussion

A HUGE thanks to the board and volunteers from the Friends of the Payette Avalanche Center for putting on another great fundraiser!  Thanks also to Jughandle Parade for the tunes as well!  That was probably the biggest fundraiser ever,  thanks also to everyone that came out and supported PAC and the FPAC!

recent observations

Yesterday, North of Brundage Ski resort, on Sgts Mountain, we ski toured in the frontal winds, there being mostly Southern. The snow did not come in until about 4pm, but we were able to observe active wind transport of loose snow that was on the surface. Slopes From East through West developed an inch thick solar crust that were already showing signs of poor bonding. WNW through ENE slopes still have soft snow on the surface.  Our pit test on a North aspect revealed a strong snowpack with moderate failures in compression 45cm/18 inches down on near surface facets where the snow gets harder (1Finger), and a lack of ability to propagate in an extended column.

 

SW aspect with an inch thick crust that does not support a skier's weight.

 

 

WNW aspect: Soft snow in Sun protected trees, and slopes with a tilt away from the Sun.

 

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 12 deg. F.
Max. temperature in the last 24 hours: 20 deg. F.
Average wind direction during the last 24 hours: ESE
Average wind speed during the last 24 hours: 9 mph
Maximum wind gust in the last 24 hours: 36 mph
New snowfall in the last 24 hours: 3 inches
Total snow depth: NA inches
weather

Area Forecast Discussion
National Weather Service Boise ID
255 AM MST Mon Feb 24 2020

.SHORT TERM...Today through Wednesday night...Cold northwesterly
flow today will bring cooler and breezy conditions with snow
showers in the West Central Mountains of Idaho. Showers will
diminish by evening. Dry conditions and light winds expected
Tuesday. A weak shortwave passage on Wednesday could bring a few
snow showers to the West Central Mountains. Temperatures will be a
few degrees below normal today. Near normal temperatures expected
by Wednesday.

.LONG TERM...Thursday through Monday...Northwest flow aloft on
Thursday will transition to southwest flow on Friday as an upper
ridge moves through the region, resulting in dry conditions and a
warming trend. Temperatures will be around 5 degrees above normal on
Thursday and around 10 degrees above normal on Friday, with lower-
valley highs in the upper 50s to lower 60s Friday. An upper trough
will expand as it enters the Western US next weekend, providing our
area with a chance of showers by Sunday. Temperatures will cool to
near normal on Sunday and snow levels will lower to around 4000
feet. The trough is expected to move east of the area on Monday as
moisture starts to spread back into the Pacific Northwest. Most of
our area is expected to remain dry on Monday with just a slight
chance of showers in Baker County and central Idaho. Temperatures
remain near normal.

&&

.AVIATION...Widespread VFR. Scattered MVFR snow showers over the
West Central and Boise Mountains through the afternoon. Surface
winds northwest 5-15 kts with gusts to around 20 kts. Winds aloft at
10k ft MSL: northwest 30-45 kts.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: A 20 percent chance of snow showers before 11am. Partly sunny, with a high near 28. Calm wind becoming west around 5 mph in the afternoon. Partly cloudy, with a low around 8. Light and variable wind. Sunny, with a high near 32. Calm wind.
Temperatures: 28 deg. F. 8 deg. F. 32 deg. F.
Wind direction: Calm---West Variable Calm
Wind speed: 5 Light 0
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: A 40 percent chance of snow showers. Partly sunny, with a high near 19. Wind chill values between zero and 10. West wind 7 to 9 mph. Total daytime snow accumulation of less than a half inch possible. Partly cloudy, with a low around 7. Wind chill values between -2 and 3. North northeast wind around 7 mph. Sunny, with a high near 26. Light and variable wind.
Temperatures: 19 deg. F. 7 deg. F. 26 deg. F.
Wind direction: W NNE Variable
Wind speed: 7-9 7 Light
Expected snowfall: less than one half in. 0 in. 0 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.