THIS AVALANCHE ADVISORY EXPIRED ON December 25, 2017 @ 6:47 am
Avalanche Advisory published on December 24, 2017 @ 6:47 am
Issued by Dave Bingaman - Payette Avalanche Center
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The primary avalanche hazard today will be found on upper elevation slopes where small,  wind slabs have formed through out the last week.  A layer of weak, faceted snow below the recent storm snow and above the Thanksgiving rain crust will also be a layer to watch as we add an additional snow load over the next few days. Buried treasure is abundant, and easy to locate, ski and ride with caution!  

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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Small isolated wind slabs were found Friday near Twin Lakes on Granite Mountain on northerly ridgelines, and Saturday in the lick Creek drainage.  These slabs were shallow ( 4-6 inches), sensitive to ski cuts but lacked the ability to propagate beyond our skis Friday. Yesterday, in the Lick Creek drainage, the wind slabs were not sensitive, and stayed put. Evidence of mid-storm natural soft wind slab avalanches were dotted around on East and NE facing steep terrain. The effects of the high winds earlier in the week were pretty obvious as well with spines and tree wells growing on ridges and sub ridges above 7000 feet.  Payette Powder Guides reported several obvious crowns on Beaverdam Peak and 8302  that had failed naturally mid slope in steep terrain following the Tuesday/Wednesday storm event.

 

Avalanche Problem 2: Persistent Slab
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There is a layer of rounding, faceted snow below the most recent storm snow,  we found this layer to be somewhat reactive as we tested for it throughout the day in hasty pits and quick shear tests.  In compression it produced low energy, non planar failures in the CT 21-25 range due to the lack of a cohesive slab above it.  We don't have enough data yet to know exactly how wide spread this layer is but we found it on multiple aspects and at multiple elevations in the Goose Lake Area, and in the Lick Creek drainage yesterday.

In addition to the upper layer of rounding, faceted snow there is a significant weak layer of faceted snow above the Thanksgiving rain crust.  Similar to the upper layer, this layer lacks a cohesive, overlying slab to create a significant avalanche problem right now.  As we add more load in the form of additional snowfall or wind loading, this layer will likely become a significant avalanche problem.  Like the upper layer, it is a widespread layer across multiple aspects and elevations.  

advisory discussion

The PAC will only be operating 3 days per week this year.  Your observations are more important now than ever before, please let us know what you are seeing while you are out riding or skiing in the local backcountry.  It's super easy to send us info and photos with date, location, pictures, general or specific snow observations, just click on the submit observations page on the PAC website and add what you saw or found in the snow.  You can also email the forecasters directly at:  forecast@payetteavalanche.org

recent observations

Yesterday, in the Lick Creek drainage, we observed just under 5 feet of snow at 6700 feet on a North aspect, with 10 inches of new snow that fell overnight making for about 20 inches of blower powder that made travel on flatter slopes more difficult.  The coverage is not to be trusted with the upper 2 feet in the snowpack not padding or covering, but hiding obstacles that lie beneath the snow, we were threading the needle between rocks and downed trees and bushes...another week or 2 of snow and settlement should help make travel much more enjoyable and safe

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The coverage looking better above 7,000 feet 

Natural, 10" thick, soft wind slab that had pulled out within the new snow Friday night towards the end of the storm.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
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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.