THIS AVALANCHE ADVISORY EXPIRED ON January 20, 2018 @ 6:38 am
Avalanche Advisory published on January 19, 2018 @ 6:38 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The avalanche hazard is Considerable above 6000 feet today.  The combination of gusty winds from multiple points on the compass and over a foot of new snow have created new wind slabs on exposed terrain.  In addition, storm slabs of 12+ inches have accumulated on a variety of old snow surfaces.  Both of these shallow instabilities will add to the complexity of this year's snowpack including the lingering possibility of triggering large avalanches on the persistent weak layer from November.

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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The storm that entered our area yesterday morning brought with it gusty winds that started from the Southeast and wrapped around the compass to the West during the day.  Wind speeds at Granite Mt were recorded near 30 mph.  The combination of a significant snowfall and wind will have created wind slabs on exposed upper elevation terrain.  These slabs are likely dense as a result of the warmer temperatures that we saw through the day yesterday and potentially brittle...ie: will be easy to trigger by skiers and sledders today.  Pay attention to changes in the texture or look of the snow pack in areas that saw the direct effects of the winds and expect newly formed wind slabs on a variety of slopes today.   Cracking, or sudden changes in how deep you are traveling in the snow pack are indicators of wind slabs.   Visibility is going to be an issue today,  expect wind slabs on upper elevation terrain and avoid them by staying on lower, wind protected slopes today.  The additional load created by these wind slabs will also increase the potential of larger avalanches failing on the weak layer formed back in November especially in shallow, rocky areas that had a thinner snow pack prior to the last 2 storms.

Avalanche Problem 2: Storm Slab
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Our snow pack just gained some weight, and will likely need a few days to adjust to the change.  Local Snotels reported over 1.5 inches of Snow Water Equivalent during the last 24 hours which is between 9 inches in the lower elevations and likely closer to 18 inches in the upper elevations.  This new snow fell on a variety of old snow surfaces including thick and thin crusts as well as a newly formed layer of faceted snow in shady and protected terrain. The National Weather Service is calling for additional snow fall throughout the day today which will add to the depth of storm slabs and increase the avalanche hazard.   Natural avalanches in the new snow are possible trending to likely today  on steeper slopes and human caused avalanches are definitely likely today which means you need to be cautious as you travel today.  Our November persistent weak layer is the wildcard in the snow pack,  the potential for larger avalanches either starting in this layer or starting shallow and stepping down into the November layer has risen significantly with the additional weight of storm and wind deposited snow.  Don't let your powder fever get the best of you today.  Your best and safest bet for the day is to avoid terrain steep enough to slide and be aware of steeper slopes around  or above you.  

advisory discussion

Please take the time to report any avalanche activity to the PAC.  You can click on the Submit Observations tab on the website or email us at: forecast@payetteavalanche.org   Photos, aspect, elevation and depth of the avalanche are great details and help us get a good picture of what is going on in the advisory area.

recent observations

Wet slide avalanches were reported from the Northern and Southern portions of the advisory area over the last week with warm temperatures in both upper and lower elevations.  In addition, skiers on a NE slope near the & Devils triggered a large avalanche (D3)last weekend that failed on the November layer of faceted snow.  

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 20 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 13 mph
Maximum wind gust in the last 24 hours: 29 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
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.