THIS AVALANCHE ADVISORY EXPIRED ON March 18, 2016 @ 6:52 am
Avalanche Advisory published on March 17, 2016 @ 6:52 am
Issued by Dave Bingaman - Payette Avalanche Center
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The Avalanche Danger today is Moderate.  On steep, Northerly aspects it is possible you may encounter isolated and sensitive windslabs near ridgelines or on smaller features that caught last weekend's windblown snow.  Warming temperatures yesterday began to settle and densifiy the 12-18 inches of new snow giving it more cohesive/slab like properties in some areas.  Pay attention to daytime warming and the effect of the sun today;  loose/wet and wet slab avalanches will become more likely on sunny aspects.

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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Strong south-southwest winds last weekend combined with moderate snowfall created some dense windslabs which are still sensitive enough for a skier or snowmobiler to trigger today. Cautious and conservative decision making on windloaded terrain will be the key to staying safe today in the mountains. Windslabs of varying thickness between a few inches and 20 + inches may be found on E, NE, N, and NW aspects.  Some of these slabs have been camouflaged by recent new snow accumulations.  The only way you are going to know what is beneath the new snow is to take the time to dig down and look for weak layers before you commit to any steep slope in windloaded terrain today. Ski cuts and sled cuts can be effective tools but with a thick windslab, you may get surprised if you arer trying to assess the slope this way.  Careful snowpack evaluation is your best bet today, also easing into steeper terrain is advised before committing to any large, committing slope.   Loose, dry avalanches or sluffs will still be a factor today if you are skiing steep, upper elevation slopes where the snow has not begun to warm yet. Plan for significant sluffing if you are committing to confined or consequential terrain. Cornices have also grown with the recent winds, give these monsters a wide berth as they are breaking wider and further back than you would  normally expect.  As the temperatures increase over the next few days, Expect to see natural cornice failures occurring as the snowpack warms.

Avalanche Problem 2: Loose Wet
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After a couple of days of cold temps and cold snow, we are going to get our spring reality check as the temperatures warm rapidly over the next couple of days. The possibility of loose, wet avalanches and thin wet slabs will be increasing as a combination of rising temperatures and the sun warm the upper portion of the snowpack.  Today, watch for wet slide activity to increase later in the day on the S and SW aspects as cloudy skies give way to partly sunny skies in the afternoon. Over the next few days expect to see point release and roller ball activity spread to the E and SE aspects as early sun hits these slopes.

recent observations

We toured on the North and South sides of the Tamarack Backcountry yesterday and found great skiing conditions on all aspects.  Near the ridgelines we found a few lingering pockets of windslab, but the real story was the warming that was taking place in the afternoon.  The light and unconsolidated snow began to settle and gain some slab like properties as the surface began getting warm.  The new snow we picked up through the day also came in much warmer than Tuesday's storm giving the snowpack a thin layer of warm snow above the colder snow below.  Hand pits, ski cuts and shear tests showed the top 4 -6 inches sluffing off in the beginning of the day and turning into more of a shallow slab later in the day especially in the mid and lower elevations.  Warming and the reappearance of the sun today are going  to  start to have a more significant effect on the snowpack. 

weather

The West Central Mountains can expect a general drying and warming trend through the weekend.  Today, expect scattered snow showers in the am and partly sunny skies this afternoon.  Overnight lows will be in the teens tonight with slightly warmer temperatures tomorrow, by Saturday day time temperatures will be 10 degrees above average with sunny skies.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Thursday Thursday Night Friday
Weather: Patchy fog before 9am. Otherwise, mostly sunny, with a high near 38. Calm wind becoming north northwest 5 to 9 mph in the afternoon. Mostly clear, with a low around 14. North wind 5 to 7 mph becoming calm in the evening. Sunny, with a high near 40. Calm wind becoming south around 5 mph in the afternoon.
Temperatures: 38 deg. F. 14 deg. F. 40 deg. F.
Wind direction: Calm then NW N Calm then S
Wind speed: 5-9 in the pm 5-7 5 in the pm
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Thursday Thursday Night Friday
Weather: Partly sunny, with a high near 31. North wind 8 to 13 mph. Mostly clear, with a low around 15. North wind 5 to 13 mph becoming east southeast after midnight. Sunny, with a high near 35. South wind 6 to 9 mph.
Temperatures: 31 deg. F. 15 deg. F. 35 deg. F.
Wind direction: N N becoming E/SE S
Wind speed: 8-13 5-13 6-9
Expected snowfall: 0 in. 0 in. 0 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.