THIS AVALANCHE ADVISORY EXPIRED ON December 24, 2015 @ 6:50 am
Avalanche Advisory published on December 23, 2015 @ 6:50 am
Issued by Dave Bingaman - Payette Avalanche Center
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The Avalanche Hazard is Moderate today. Pockets of Considerable Hazard exist near ridge tops where S and SW winds have created sensitive wind slabs in the new snow. Wind slabs may also be encountered on E or W facing slopes especially in gullies or other small scale terrain features that catch the blowing and drifting snow. Overall, the new snow is bonding well to the older snow layers below creating a deep, dry, user friendly snowpack throughout the area.

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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Parts of the PAC advisory area saw sustained winds in excess of 35 mph on Monday.  Gusts climbed over 50 mph.  With the amount of snow we received, that equals some serious wind transport.  Be aware that you could trigger a shallow or deep wind slab on upper elevation wind loaded slopes for the next few days. Cold temperatures do a great job preserving wind slabs and other weaknesses in the snowpack. You will be able to spot wind affected slopes literally from a mile away, look for sculpted or pillowed features as you make your terrain choices.

Avalanche Problem 2: Storm Slab
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The West Central Mountains have recieved over 4 feet of snow in the last 7 days.  Overall the bonds between these different storm layers are pretty good, but we are still finding signs of instability at density changes within all this new snow. We found over 300cm (just about 10 ft) of snow yesterday in a wind loaded N facing bowl near Fisher Creek Saddle. Throughout the advisory area, we are seeing snow depths similar to what we would normally see much later in the season with most upper elevations in the 6-7 foot range.  Bottom line is that you may still trigger one of these instabilities in the new snow on unsupported, steep rollovers or other convex slopes. See the pit tests from yesterday for depths and scores.

Avalanche Problem 3: Loose Dry
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Loose dry avalanches are a good problem to have, they mean you have deep, dry snow that is soft enough to move around when disturbed...most of the time these "sluffs" are pretty manageable. We saw a lot of moving snow yesterday on steeper slopes and while they are moving relatively slow and small right now, they could still push you off course on a sled or skis.  Be aware of sluff potential and your options if you are riding or sliding in steep, confined terrain or terrain with obstacles or cliffs below you.

recent observations

George and I took advantage of the mostly clear skies and checked out the steep terrain north of Granite Mt, Hard Creek, near Duck Lake and throughout the headwaters of Fisher Creek yesterday.  Conditions were much better than we anticipated earlier in the week based on the storm totals and wind that our advisory area got hit with. We saw little evidence of the natural storm snow avalanche cycle that we had anticipated. Our snowpits showed relatively good bonding within the new snow layers with some failures at density changes within the new snow layers, because of the lack of cohesion within the new snow these weaknesses lacked the ability to propagate in our Extended Column Tests or during sled cuts on steep rollovers.  Based on the Red Flags we saw waving at the beginning of this storm cycle we got pretty lucky as the new snow piled up. Bear in mind that you may still encounter some pockets of touchy wind slab and utilize good travel protocols: one at a time on slopes, keep your eyes on your partners and ride or ski with all of your avy gear on your body.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: no data deg. F.
Max. temperature in the last 24 hours: deg. F.
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Total snow depth: inches
weather

Our powder forecast continues to look great through Christmas Eve with high pressure building over the weekend and pushing the next few storms to the South of the West Central Mountains.  With moderate accumulations and cooler temperatures over the next 48 hours, the new snow is going to be blower dry.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow showers likely. Cloudy, with a high near 25. Wind chill values between zero and 10. Southwest wind 7 to 9 mph. Chance of precipitation is 70%. Total daytime snow accumulation of 1 to 2 inches possible. Snow showers likely. Cloudy, with a low around 15. South wind 3 to 6 mph. Chance of precipitation is 60%. New snow accumulation of 1 to 2 inches possible. Snow showers likely. Cloudy, with a high near 24. Calm wind becoming south 5 to 7 mph in the afternoon. Chance of precipitation is 70%. New snow accumulation of 1 to 2 inches possible.
Temperatures: 25 deg. F. 15 deg. F. 24 deg. F.
Wind direction: Southwest South South
Wind speed: 7-9 3-6 Calm becoming 5-7 in the afternoon
Expected snowfall: 1-2 in. 1-2 in. 1-2 in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow showers. High near 21. Wind chill values between zero and 5. Breezy, with a west southwest wind 15 to 21 mph. Chance of precipitation is 80%. New snow accumulation of 2 to 4 inches possible. Snow showers likely. Cloudy, with a low around 11. Wind chill values between -2 and 7. Breezy, with a southwest wind 16 to 20 mph. Chance of precipitation is 70%. New snow accumulation of 3 to 5 inches possible. Snow showers. High near 20. Wind chill values between -5 and 5. Breezy, with a south southwest wind 15 to 20 mph. Chance of precipitation is 80%. New snow accumulation of 2 to 4 inches possible.
Temperatures: 21 deg. F. 11 deg. F. 20 deg. F.
Wind direction: West West/Southwest Southwest
Wind speed: 15-21 16-20 15-20
Expected snowfall: 2-4 in. 3-5 in. 2-4 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.