THIS AVALANCHE ADVISORY EXPIRED ON March 6, 2016 @ 7:16 am
Avalanche Advisory published on March 5, 2016 @ 7:16 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The Avalanche Danger is Moderate today. Rain, above average temperatures and winds gusting above 30 mph will increase the avalanche danger. Loose/wet avalanches will be possible on steep, lower and mid elevation slopes.  Northerly slopes where small, isolated wind slabs persist and heavily corniced areas will have potential for shallow, natural or human caused avalanches as gravity and warm temperatures take their toll on the snowpack today. Snowlines will lower by mid day increasing the windslab hazard on leeward slopes.

 

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Loose Wet
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The possibility of Loose/Wet slides will be increasing today. Rain and warm temperatures are going to have an effect on the snowpack.  The duration and amount of rain will be the determining factors today on the avalanche danger.  If the snowpack becomes saturated before it has a chance to refreeze, wet slabs may also become more likely especially on slopes with older crusts buried below the surface. Rain on snow, warm temperatures,  and high winds are all red flags that you can't ignore in the mountains. Large, overhanging cornices and lingering windslabs that get saturated will be tested on the leeward aspects. Travel below heavily corniced areas today is not a good idea. Paying attention to changing conditions is going to be essential!

Avalanche Problem 2: Wind Slab
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Winds are forecasted to be out of the South and Southwest today steady in the mid 20 mph range with gusts into the 30+ range. New, dense windslabs will be likely on the northerly aspects while East and West aspects will begin to get crossloaded as winds intensify combined with increasing snow showers later in the day. Higher winds and additional snow overnight will add to the problem.

recent observations

We toured around the Northern aspects of Squaw Point yesterday and found a solid snowpack with a few areas of thin windslab on leeward aspects. These windslabs were unreactive in our hasty pits and did not fail on ski cuts or sled cuts.  Rain on these remaining windslabs combined with a thick layer of Grauple deposited on Thursday will have the potential to increase their sensitivity especially if wind transport of the new snow is occurring later in the day today. Tomorrow is going to be a different world in the mountains and caution will need to be part of your travel plan as additional rain today, new snow, high winds and above average temperatures change conditions literally overnight.

Large cornices near Lava Point on Thursay that were already failing before the rain.

 

weather

RAIN and above average temperatures will be the theme today and tomorrow.  A cold front will likely bring snowlines down to the valley floors by mid day tomorrow.  Today expect a high near 43 degrees at 7700 feet with increasing S and SW winds.  Total snow accumulation will be 2-4 inches today with an additional 1-3 overnight. Winds will increase later in the day today with gusts overnight expected to be near 55 mph as a cold front enters our area.  Tomorrow brings the bulk of the moisture plume to the West Central with 3-7 inches of  snow forecasted and a short lived cooling trend to start the week.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Saturday Saturday Night Sunday
Weather: Showers, mainly before 11am. High near 46. South wind 9 to 11 mph. Chance of precipitation is 90%. Rain, mainly after 11pm. Low around 36. Breezy, with a southeast wind 10 to 15 mph increasing to 18 to 23 mph in the evening. Winds could gust as high as 32 mph. Chance of precipitation is 90%. Showers. High near 42. South wind 8 to 17 mph becoming north in the morning. Chance of precipitation is 100%.
Temperatures: 46 deg. F. 36 deg. F. 42 deg. F.
Wind direction: S SE S becoming N later in the morning.
Wind speed: 9-11 10-15 gusting to 32 8-17
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Saturday Saturday Night Sunday
Weather: Rain and snow showers, becoming all snow after 11am. High near 43. Breezy, with a south southwest wind 21 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 90%. New snow accumulation of 2 to 4 inches possible. Rain and snow, mainly after 11pm. Low around 34. Windy, with a south wind 21 to 26 mph increasing to 35 to 40 mph after midnight. Winds could gust as high as 55 mph. Chance of precipitation is 90%. New snow accumulation of 1 to 3 inches possible. Rain and snow showers, becoming all snow after 11am. High near 38. Windy, with a south southwest wind 21 to 31 mph becoming west 7 to 12 mph in the afternoon. Winds could gust as high as 41 mph. Chance of precipitation is 100%. New snow accumulation of 3 to 7 inches possible.
Temperatures: 43 deg. F. 34 deg. F. 38 deg. F.
Wind direction: S/SW S/SW S/SW
Wind speed: 21-23 gusting to 32 21-26, increasing to 35-40 gusting to 55 21-31 gusting to 41
Expected snowfall: 2-4 in. 1-3 in. 3-7 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.