THIS AVALANCHE ADVISORY EXPIRED ON February 2, 2016 @ 6:37 am
Avalanche Advisory published on February 1, 2016 @ 6:37 am
Issued by -
bottom line

The avalanche danger is CONSIDERABLE at upper elevations. Human triggered avalanches are likely on steep slopes where Friday's snow combined with moderate to high winds caused new wind slabs to form. You are most likely to trigger an avalanche below exposed ridge lines, near cliff bands, or where buried surface hoar is still present. At middle and low elevations the wind affected slopes are more wide spread and the danger is MODERATE

How to read the advisory


  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Wind slabs remain our primary concern today. With the new snow and wind on Friday expect to find wind slabs on north, northeast, northwest and cross loaded west and east aspects. You are most likely to find these slabs at or near the ridge tops or in exposed terrain above 7,000 feet. They are still relatively widespread in the upper and middle elevations and range in sensitivity from touchy to unreactive. Shallow wind slabs are more likely right now but you may also find some deeper ones still lingering under a layer of new snow. These slabs range in density between soft to hard, which means they may let you get well out onto them before they fail. Also, keep in mind that some of these wind slabs may be resting on a new layer of buried surface hoar that was formed early last week, or even worse could step down to buried surface hoar that formed in early January.

Avalanche Problem 2: Persistent Slab
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While we are still thinking about and looking for the early January buried surface hoar, we now have a new crop of preserved surface hoar that was buried under Friday's new snow. Slightly higher temperatures during the Thursday/Friday Storm resulted in a slab overlying the surface hoar that ranges in density from light powder in shaded high elevations, to fairly dense in middle elevations. This new slab will be our primary concern as we start the month of February. Use caution and good travel protocols if you are skiing and riding in avalanche terrain.  These buried surface hoar layers have the potential to spread out or propagate over large areas when triggered and are the type of layer responsible for the majority of avalanche incidents and fatalities. Take the time to look for buried surface hoar on slopes before committing to any terrain steep enough to slide. If you are unsure, stick to slopes less than 30 degrees.

advisory discussion

It is with a heavy heart this morning that I write about an avalanche yesterday near McCall, that unfortunatley resulted in a single fatality. PAC Forecasters will be heading out to the accident site this morning to gain as much information as possible. Our condolences to the victims family and friends. 

Crown of yesterday's avlanche seen in picture above.

recent observations

Went up Lick Creek yesterday to the Black Lee Creek drainage. Solar aspects were starting to sluff in the sun at high elevations, and a new round of surface hoar was observed on north and northeast aspects. We dug a pit at 6900 feet on a north-northeast aspect looking to find buried surface hoar, we were pleased to not find any. The snow pack we did find was 'right side' up in hardness and the only results we did get were a CT 19-Q2 resistant planar 80cm from the surface (density change from 4 finger to 1 finger). The extended column test performed proved futile in this particular spot with a result of ECTX (no fracture).

weather

Starting off today with wind chills sub zero degrees Fahrenheit. There is a chance for isolated showers, but expect to see the sun come and go. The high will be in the low 20's with a north wind blowing 5-10. More of the same for the next two days, with the next chance for measurable precipitation on Thursday.

 

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: Patchy fog before 11am. Otherwise, partly sunny, with a high near 26. Light northwest wind. A 20 percent chance of snow showers before 11pm. Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 0. Calm wind. Patchy fog before 11am. Otherwise, mostly cloudy, with a high near 26. Wind chill values between zero and 10. Light south wind.
Temperatures: High 26 deg. F. Low 0 deg. F. High 26 deg. F.
Wind direction: Northwest South
Wind speed: Light Calm Light
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: Isolated snow showers. Mostly cloudy, with a high near 22. Wind chill values between -4 and 6. North wind 8 to 10 mph. Chance of precipitation is 20%. A 30 percent chance of snow showers, mainly before 11pm. Mostly cloudy, with a low around 6. West wind 3 to 7 mph. New snow accumulation of less than a half inch possible. A 20 percent chance of snow showers after 11am. Mostly cloudy, with a high near 22. Wind chill values between -2 and 8. West southwest wind 3 to 5 mph.
Temperatures: High 22 deg. F. Low 6 deg. F. High 22 deg. F.
Wind direction: North West West-southwest
Wind speed: 8-10 3-7 3-5
Expected snowfall: 0 in. Less than half an inch 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.