THIS AVALANCHE ADVISORY EXPIRED ON February 21, 2019 @ 6:58 am
Avalanche Advisory published on February 20, 2019 @ 6:58 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The Avalanche Hazard is Moderate today. Natural Avalanches are unlikely and Human caused Avalanches are possible.  Wind slab hazard exists on upper elevation, wind loaded, and exposed slopes. It may be difficult to recognize wind slabs as they have been hidden by new snow.  Travel cautiously in and around Cornices and wind loaded terrain.

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 ?
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  • Likelihood ?
    Certain
    Very Likely
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  • Size ?
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Wind slabs are still on our radar. The freshest crop of wind slabs vary from 3-6 inches deep. Over the last couple days we have seen calmer winds and light snow that has covered up any of the usual signs that would indicate a wind slab. Cornices are big, and overhanging right now, and are a good indicator of wind loaded terrain. Travel cautiously in and around wind loaded avalanche terrain and corniced ridge lines.  

We did have a shallow wind slab crack yesterday as I rode over it on Granites upper East face. It was sitting on some surface hoar that likely formed on Sunday-Monday under clear skies during our brief break in storms. We covered a lot of ground and didn't see anymore signs of instability, but its a good reminder to always play it safe and spread out in steep terrain, traveling one at a time, and keeping your eyes on your partner from a safe place.

 

 

 

advisory discussion

PAC will issue 3 Advisories per week through the remainder of the winter as long as funding is available.

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, Duck Lake, Slab Butte Area and found great riding conditions and pretty good stability. Our weather station on Granite collected a lot of rhime during the last storm cycle and had stopped giving us wind data. We got it cleaned up and is now back online.  My 10 foot probe is was just below the snow surface! The mountains are "fat" right now, and coverage is finally where we want it. 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 7 deg. F.
Max. temperature in the last 24 hours: 26 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: NA mph
Maximum wind gust in the last 24 hours: NA mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

 

 

 

 

Area Forecast Discussion
National Weather Service Boise ID
257 AM MST Wed Feb 20 2019

.SHORT TERM...Today through Friday...Low pressure system will
continue to move slowly southward through the region today and
tonight. Overnight, we have received about an inch of snow at the
Boise Airport, and around 4 inches in McCall. Even a light
dusting of snow may cause travel problems this morning as
temperatures remain below freezing. Widespread light snow will
continue through this morning, but will transition to snow showers
this afternoon. Additional accumulations of up to an inch, with
locally 2 inches, are expected in the valleys, and 2 to 4 inches
(locally 6 inches) in the mountains. A Winter Weather Advisory
will remain in effect today across southeast Oregon and southwest
Idaho, although conditions will improve in the valleys during the
afternoon as temperatures rise above freezing. As the low
continues to push southward tonight, the snow showers will
decrease, except for the Owyhees and Idaho highlands along the
Nevada border where the snow showers are expected to persist due
to the closer proximity to the upper low. Therefore, the Winter
Weather Advisory will continue in those areas through Thursday
morning. A weak upper ridge will bring dry weather to the area
Thursday night through Friday. Temperatures will remain below
normal.

.LONG TERM...Friday night through Wednesday...A cool and
unsettled start to the extended periods as another upper low drops
south from off the British Columbia coastline early Saturday.
Widespread snow will persist through the weekend. A series of
disturbances get caught up in the upper level flow leaving a
chance for precipitation throughout the period. By the end of the
period, a warm frontal feature moves in lifting snow levels back
up above 3k feet MSL meaning a wintry mix for valleys if not a
full change over to rain by mid-week. Temperatures stay below
normal through much of the period then hit normal again by
Wednesday.

&&

.AVIATION...MVFR/IFR conditions as snow continues to fall.
Afternoon hours will bring spotty showers throughout the region. A
slow tapering off by late Wednesday into early Thursday with a
few showers remaining in the central Idaho mountains. Surface
winds, west-northwest 5-10kts. Winds aloft to 10k feet MSL,
northwest-north 15-20kts.

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 snow showers likely after 11am. High near 27. Light and variable wind. Chance of precipitation is 90%. Total daytime snow accumulation of around an inch possible. A 50 percent chance of snow showers. Mostly cloudy, with a low around 14. Northwest wind around 5 mph becoming north northeast after midnight. New snow accumulation of less than one inch possible. A 20 percent chance of snow showers after 11am. Partly sunny, with a high near 28. North northwest wind around 6 mph.
Temperatures: 27 deg. F. 14 deg. F. 20 deg. F.
Wind direction: Variable NNW-NNE NNW
Wind speed: Lighrt 5 6
Expected snowfall: 1 in. Less than one in. 0 in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow before 11am, then snow showers after 11am. High near 19. South wind around 5 mph becoming light and variable. Chance of precipitation is 90%. Total daytime snow accumulation of 2 to 4 inches possible. Snow showers likely, mainly before 11pm. Mostly cloudy, with a low around 10. Wind chill values between zero and 5. Northeast wind around 9 mph. Chance of precipitation is 70%. New snow accumulation of 1 to 2 inches possible. A 30 percent chance of snow showers, mainly after 11am. Partly sunny, with a high near 19. Wind chill values between zero and 8. Northeast wind around 9 mph. New snow accumulation of less than a half inch possible.
Temperatures: 19 deg. F. 10 deg. F. 19 deg. F.
Wind direction: S NE NE
Wind speed: 5 9 9
Expected snowfall: 2-4 in. 1-2 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.