THIS AVALANCHE ADVISORY EXPIRED ON December 30, 2016 @ 5:55 am
Avalanche Advisory published on December 29, 2016 @ 5:55 am
Issued by George Halcom - Payette Avalanche Center
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The avalanche danger is Considerable today above 6,000 feet. Below 6,000 feet, the avalanche danger is Moderate. Skiers and riders could possibly trigger avalanches in steep, wind loaded terrain.

How to read the advisory


  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Most of the wind slabs that formed during our pre-Christmas storm have settled out to a large degree and won't be nearly as sensitive today. However, just as one batch of wind slabs are healing, another round of wind slabs formed during this last storm from winds out of the west southwest.

Also keep in mind, a fresh wind slab avalanche has the potential to 'step down' into older layers of snow causing for an avalanche that has the possibility of being several feet deep, and be sure if you are traveling into steep committing avalanche terrain, to find some test slopes and/or dig a few quick holes to see how the snowpack has adjusted to the new snow and wind.

 

Avalanche Problem 2: Loose Dry
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It will be possible to trigger loose, dry avalanches as we wait for this last bit of snow to consolidate over the next few days. Keep up safe protocols in steep avalanche terrain. Loose snow can sweep you off your feet, and carry you into places you would rather not go like over cliffs, and into gullys.

Avalanche Problem 3: Storm Slab
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If traveling in avalanche terrain that has not seen the affects of wind, there is a possibility of triggering a soft storm slab. These will be in very isolated areas. 

advisory discussion

 We have found a persistent weak layer near the ground throughout the advisory area over the last two weeks that is made up of weak faceted snow or a combination of facets and old crusts left over from our early season snowpack.  The weak layer of facets is fairly widespread and well developed in the upper elevations especially on the shadier aspects where early snowfall accumulated. Shallow rocky areas are also harboring this layer on other aspects.  George described this problem last week as a low probability/ high consequence avalanche problem...meaning you are not very likely to trigger a slide this deep but the consequences if you did would be bad.  The 3-5 foot overlying slab is gaining strength which is good but is also turning into more of a hard, consolidated slab if it fails. Now is a good time to play it safe on steep shady slopes or slopes with thinner/rocky areas where you are more likely to trigger the weak layer.  

This kind of problem is both difficult to trigger and more difficult to predict.  Slopes with tracks on them are not a good indicator of stability as the trigger points are likely to be isolated to thin or weak spots that are hard to find or easy to miss.  Remember that a lack of red flags or signs of instabilities is not a good indicator for a deep or persistent slab problem.  Don't let the lack of evidence lull you into more consequential terrain or sloppy group management.  Use good travel techniques(one at a time) and watch your partners if you are riding or sliding in this type of terrain.

 

PAC still has room for both skiers and snowmobilers in our upcoming Intro to Avalanches class on Jan 6 and 7, registration by email is required.

Friends of the Payette Avalanche Center needs YOU! Come join us on Tuesday January 3rd at Idaho First Bank in McCall at 6 pm for an annual membership meeting. This meeting is open to the entire snow loving community,  and we need to hear from you on how the Payette Avalanche Center should grow into the future.

Did you know: Only a small portion of our operating budget comes from the Forest Service, we RELY on the the Friends of Payette Avalanche Center to help finance the forecasts that you use. Please come out and have your voice be heard and show your support!

recent observations

Tuesday, on Sgt's Mountain, just North of Brundage, we saw  multiple naturals: 2 on East aspect skiing out  in the new snow/wind blown snow.  The East side of ridge had a firm layer under new wind slabs.  There was widespread cracking and we had a nice remote trigger about 50 feet wide by 12-18 inches deep on East Aspect.  Also saw R3, D1.5 natural on 44 Run NNW aspect with 12-18 inch crown.  Had multiple CTM on East pit at 35 cm.  CTE on NNW at 30 in a protected spot.  Could not find SH in that protected pit.  Have a good day, I'll see you Thursday AM.

Remember, your information can save lives. If you see anything we should know about, please participate in the creation of our own community avalanche advisory by submitting snow and avalanche conditions. You can email the forecasters directly at forecast@payetteavalanche.org

weather

Today, a mild temperature inversion will set in briefly until Saturday, giving us slightly milder temperatures in the upper elevations than in the valley. High temperatures in the upper elevations should climb up to around 27 degrees while the valley will only see a high temperature of 21 degrees. Winds will be in the teens out of the South/Southwest. The next system will move in Friday bringing light snow, and a cold front Saturday evening. Temperatures going into next week will be some of the coldest of the season.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Thursday Thursday Night Friday
Weather: Areas of dense fog before 11am. Otherwise, mostly sunny, with a high near 21. Wind chill values between -4 and 6. South wind 6 to 8 mph. Areas of dense fog. Otherwise, partly cloudy, with a low around 11. South wind 6 to 8 mph. Snow likely, mainly after 11am. Areas of fog before 11am. Otherwise, cloudy, with a high near 25. South wind 5 to 7 mph becoming light and variable. Chance of precipitation is 60%. New snow accumulation of less than one inch possible.
Temperatures: High 21 deg. F. Low 11 deg. F. High 25 deg. F.
Wind direction: South South South
Wind speed: 6-8 3-6 5-7
Expected snowfall: 0 in. 0 in. less than one in.
Granite Mountain at 7700 feet.
  Thursday Thursday Night Friday
Weather: Areas of fog before 11am. Otherwise, partly sunny, with a high near 27. Wind chill values between -1 and 9. South southwest wind 11 to 17 mph. Areas of fog after 11pm. Otherwise, increasing clouds, with a low around 18. South wind around 16 mph. Snow likely, mainly after 11am. Areas of fog before 11am. Otherwise, cloudy, with a high near 24. South wind 9 to 15 mph becoming west in the afternoon. Chance of precipitation is 70%. New snow accumulation of 1 to 2 inches possible.
Temperatures: High 27 deg. F. Low 18 deg. F. High 24 deg. F.
Wind direction: South-southwest South South becoming West
Wind speed: 17 16 9-15
Expected snowfall: less than one in. 0 in. 0 in.
Disclaimer

This avalanche advisory is provided through a partnership between the Payette National Forest and the Friends of 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.