THIS AVALANCHE ADVISORY EXPIRED ON March 17, 2016 @ 7:15 am
Avalanche Advisory published on March 16, 2016 @ 7:15 am
Issued by Dave Bingaman - Payette Avalanche Center
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The Avalanche Danger is MODERATE today.  Areas of  highest concern will be on upper elevation, windloaded E, NE, N, and NW slopes where it remains possible for skiers and riders to trigger dense windslabs in steep, exposed terrain. In wind protected terrain soft storm slabs and loose dry avalanches will be your main concern.Human triggered avalanches will be possible on slopes over 35 degrees. Pay attention to the effects of daytime warming or direct sun on the new snow today.

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 yesterdays new snow that came in without much wind but in some areas you may still see the visual clues of windloading and sculpting.  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 your trying to assess the slope this way.  Careful snowpack evaluation or avoidance is your best bet today, there is plenty of good riding and skiing to be had without getting into steep windloaded areas today.  With the high winds that we experienced Saturday and Sunday, you may find some of these windslabs further down slope than you would usually expect. Look for pillows, or areas of wind deposited snow below steep headwalls or cliffbands as well as near the ridgelines.  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 cornice failures occurring as the snowpack warms.

 

 

Avalanche Problem 2: Loose Dry
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A combination of dry, loose avalanches and loose, mostly unconsolidated storm slabs will be found on wind protected terrain today. With 18" of unconsolidated snow on the ground use caution on slopes over 35 degrees especially around terrain traps and tree wells. These soft slabs and sluffs can easily push you or your sled where you don't want to go or into or over obstacles below. Good, safe travel protocols are essential today: don't  put more than 1 person at a time on steep slopes and  keep your eyes on your partners.

Multiple layers of grauple can be found in the upper 2 feet of the snowpack. Grauple is a  tricky weak layer and a good snow type for fast moving loose,dry avalanches.    Shallow storm slabs may also be found in protected terrain where the new snow is resting on a variety of old snow surfaces including old crusts and buried grauple layers.  These slabs are very soft almost to point of not being a true slab, the biggest danger today would be getting knocked down and having your sluff or one of these soft slabs cover you up. 

recent observations

 

The amount of precipitation we received over the last 36 hours was a bit of a surprise. The intensity of yesterday's snowfall was a shocker. We traveled out the Goose Lake Rd and found upwards of 6" near Goose Lake with just about 18" of new near Duck Lake at 7500 ft. We ended our day near Fisher Saddle and were surprised that we saw between 1 and 2 inches of snowfall/hour for most of the day.  The 18 inches of new snow came in over the last few days with relatively light winds and was just starting to break down last week's most recent rain crust which made the snow feel even deeper on snowmobiles. We both had some epic powder turns and some epic sticks as the snow continued to pile up through the day.

weather

A moisture laden NW flow developed over the last 2 days and left us with quite a bit more snow than the models and the NWS forecast were originally predicting. Today we can expect to see an additional 1-2 inches in the mountains. The moisture tap will begin to turn off this afternoon with a drying trend, expect increasing temperatures over the next few days with a return to 10 degree above average temperatures over the weekend. Winds are going to be increasing slightly today and will be shifting from SW today to N/NW tonight. High temperature for today will be around 31 with lows tonight in the teens.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Wednesday Wednesday Night Thursday
Weather: Scattered snow showers. Cloudy, with a high near 36. Calm wind becoming southwest 5 to 7 mph in the afternoon. Chance of precipitation is 40%. New snow accumulation of less than a half inch possible. A 20 percent chance of snow showers before midnight. Mostly cloudy, with a low around 16. Southwest wind around 6 mph becoming calm in the evening. Mostly sunny, with a high near 39. Calm wind becoming north northwest 5 to 7 mph in the afternoon.
Temperatures: 36 deg. F. 16 deg. F. 39 deg. F.
Wind direction: SW SW N/NW
Wind speed: 5-7 6 5-7
Expected snowfall: Trace in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: Scattered snow showers. Cloudy, with a high near 31. Southwest wind 7 to 11 mph. Chance of precipitation is 50%. New snow accumulation of 1 to 2 inches possible. A 30 percent chance of snow showers before midnight. Mostly cloudy, with a low around 18. West wind 7 to 10 mph becoming north northwest after midnight. New snow accumulation of less than a half inch possible. Mostly sunny, with a high near 32. North wind 9 to 11 mph.
Temperatures: 31 deg. F. 18 deg. F. 32 deg. F.
Wind direction: SW W then NW N
Wind speed: 7-11 7-10 9-11
Expected snowfall: 1-2 in. Trace 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.