THIS AVALANCHE ADVISORY EXPIRED ON February 14, 2016 @ 7:04 am
Avalanche Advisory published on February 13, 2016 @ 7:04 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The avalanche danger is MODERATE on slopes steeper than 35 degrees, above 7,000 feet in elevation. Warm temperatures, with a mild freezing that just began late last night, are slowly working to re-freeze our snowpack, and our buried surface hoar layer.  Below 7,000 feet generally safe avalanche conditions exist and the danger is LOW. 

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
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Loose, wet avalanches occur when water is running through the snow pack. Our chances of loose, wet slides are dwindling, but with a lack of freezing temperatures over the last few days in the upper elevations due to the latest inversion, we will have to wait a bit longer to let our snow pack set-up. We have just had a brief freeze late last night that should help stabilize the snow surface, but temperatures are forecasted to rise again this evening. 

Avalanche Problem 2: Persistent Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Persistent Slab avalanches can be triggered days to weeks after the last storm.They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.

Triggering a slab due to this weak layer is becoming more difficult, but I would not let my guard down, especially during times of warm ups where water is running in the snowpack. Take the time to carefully assess terrain choices on the north half of the compass today. Especially areas where the snow cover is thinner which allows the buried surface hoar to be closer to the surface, and in turn more reactive---especially for snowmachines. 

We have been tracking two persistent weak layers in the top three feet of our snow pack. One is buried deeply and was blanketed by the MLK storm cycle, the other near the surface. The warm temps and direct sun light is making the layer closer to the surface hard to find. The deeper buried layer is not as easily affected by sun and warm temps and remains intact on north facing slopes that are protected from direct solar radiation. We are tracking this weak layer, and are finding it better preserved/ more reactive in some places than others. This is the same layer that is the cause of the fatal avalanche on January 31st. A persistent weak layer such as this is a low probably, but HIGH CONSEQUENCE scenario. 

 

advisory discussion

FPAC FUNDRAISER!!

The Friends of the Payette Avalanche Center (FPAC) is vital to the operation of the Payette Avalanche Center, and they need your support!

This Saturday evening at the Little Ski Hill from 6-9 PM.  Some of the goods: Beer from McCall's own SRB, Waverunner rental from Cheap Thrills, Jug Mountain Ranch Mountain Bike Shuttles and skis from Dynafit! Practice up with those beacons and get ready for some timed beacon races with great prizes.  Family Friendly environment with night skiing, BBQ and plenty of parking available on both sides of the highway. Thanks to all the donors that have supported us in the past and again this year! Kids are FREE at the door (does not include night skiing).

recent observations

Thursday, we toured out to Box lake in a snowpack that felt more like water. Creeks are open and flowing strong. The upper 4 inches of the snowpack was saturated from the continued warm, inverted temperatures. Even Northern slopes had some rollerballs peeling off the ridges...putting debris on all aspects. South and West slopes had a fair amount of loose, wet debris from slides over the last few days. We were able to find our persistent slab problem weak (buried surface hoar) layer about 80cm down, but could not get it to fail in our stability tests. 

weather

Light snow this morning won't add up to more than an inch. Temperatures in the mountains will be a bit cooler, around 33 degrees, than in the valley as the inversion has moved out. Winds will be outof the West around 15MPH. Tonight, temperatures should rise a little: around 32 by 4AM, but increase chances of precipitation bringing in around 1-3 inches of snow with a Southwest wind 10-14 MPH.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Saturday Saturday Night Sunday
Weather: Scattered rain and snow showers before 11am. Cloudy, with a high near 36. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 40%. New snow accumulation of less than a half inch possible. Snow, mainly after 11pm. Low around 28. Light south southeast wind. Chance of precipitation is 100%. New snow accumulation of 1 to 2 inches possible. Snow before 11am, then rain and snow. High near 36. Calm wind becoming south southeast around 5 mph in the afternoon. Chance of precipitation is 90%. New snow accumulation of around an inch possible.
Temperatures: High 36 deg. F. Low 28 deg. F. High 36 deg. F.
Wind direction: South South/Southeast South/Southeast
Wind speed: Calm-5MPH Light 5 MPH
Expected snowfall: less than half in. 1-2 in. 1 in.
Granite Mountain at 7700 feet.
  Saturday Saturday Night Sunday
Weather: Scattered snow showers, mainly before 11am. Cloudy, with a high near 33. West wind 6 to 15 mph. Chance of precipitation is 50%. New snow accumulation of less than one inch possible. Snow. Temperature rising to around 32 by 4am. South southwest wind 10 to 14 mph. Chance of precipitation is 100%. New snow accumulation of 1 to 3 inches possible. Snow. High near 38. West wind 9 to 14 mph. Chance of precipitation is 90%. New snow accumulation of 2 to 4 inches possible.
Temperatures: High 33 deg. F. Low 32 deg. F. High 38 deg. F.
Wind direction: West Sout/Southwest West
Wind speed: 6-15 MPH 10-14 MPH 9-14 MPH
Expected snowfall: less than one in. 1-3 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.