THIS AVALANCHE ADVISORY EXPIRED ON January 15, 2016 @ 7:01 am
Avalanche Advisory published on January 14, 2016 @ 7:01 am
Issued by -
bottom line

New snowfall yesterday combined with moderate to strong winds has caused the danger to rise to CONSIDERABLE above 7,000 feet on all steep wind loaded slopes. Fresh wind slabs have formed on a variation of different surfaces on all leeward slopes. If traveling above 7,000 feet human caused avalanches are likely. Below 7,000 feet the danger is MODERATE due to wind slabs and storm slabs from yesterdays snowfall.

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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Boy howdy! The winds were a whippin' yesterday. While the primary wind direction was south-southwest, localized wind shifting due to high winds speeds was evident throughout the afternoon. So be on the look out for wind slabs in likely and unlikely places (below cliffs, cross-loaded slopes) . These new wind slabs are going to be reactive on all leeward (downwind) aspects over 30 degrees that have obvious signs of wind loading (smooth rounded pillow like snow surface) and could range from 6 inches to 3 feet in depth. The tricky part about our current conditions, is that due to the high winds yesterday, these wind slabs could be located mid-slope on steep open faces. This will allow you to get half way down a slope before getting into trouble. The best bet is to avoid all slopes over 30 degrees until these wind slabs are no longer reactive.

Avalanche Problem 2: Storm Slab
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With a the snow falling on a known weak layer yesterday, storm slabs will be found on slopes above 7,000 feet and over 30 degrees. Be on the look out for any natural avalanche activity and/or crack/whoomping. These are Red Flags that the snow is not safe on that particular aspect/slope angle and needs more time. Fortunately storm slabs can heal quickly, so be patient and stick to low angle terrain until our snowpack has had time to adjust.

advisory discussion

Conditions in the backcountry above 7,000 feet on slopes over 30 degrees warrent respect and patience. With 6-12 inches of new snow and the perfect making of an avalanche (surface hoar/facets with a new slab on top) these are prime condintions to get into trouble if you do not carefully evaluate the snowpack and make conservative decisions. Keep to low angle slopes in sheltered terrain today and enjoy the creamy low angle powder.

recent observations

We went up Warren Wagon Road yesterday to see the how the new snow and wind was interacting with the surface hoar/near surface facets that had formed over the weekend and early this week. The short answer, not well. At upper elevations (above 7,000) the snow that fell (6-12 inches) is having a hard time bonding to the variety of old surfaces. Where there was sun crust on exposed ridges (solar aspects), the wind scoured and blew the new snow away making for fast skinning, but bad skiing. On all sheltered leeward slopes (north half of compass) the new snow was very reactive on the existing surface hoar/near surface facets laden slopes. While the snow was reactive yesterday it had not consolidated into a cohesive slab, that most likely has changed as this new snow has consolidated over night.

weather

Yesterday was the definitely a storm day. With winds sustaining in the 20's and gusting to into the 40's at 8,000 feet the new snow was blowing and loading at a very rapid pace. It seems as though we got the bulk of the storm yesterday however, today expect to see scattered showers with winds in the teens at upper elevations. Temperatures will be in the 20's and less than an inch of snow is forecasted.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Thursday Thursday Night Friday
Weather: Isolated snow showers. Patchy fog before 11am. Otherwise, cloudy, with a high near 27. Light and variable wind. Chance of precipitation is 20% A 50 percent chance of snow after 11pm. Cloudy, with a low around 19. Light east southeast wind. New snow accumulation of less than one inch possible. A 50 percent chance of snow. Cloudy, with a high near 28. Light and variable wind. New snow accumulation of less than a half inch possible.
Temperatures: High 27 deg. F. Low 19 deg. F. High 28 deg. F.
Wind direction: Variable E/SE Variable
Wind speed: Light Light Light
Expected snowfall: 0 in. Less than 1 in. Less than 0.5 in.
Granite Mountain at 7700 feet.
  Thursday Thursday Night Friday
Weather: Scattered snow showers, mainly before 11am. Patchy fog before 11am. Otherwise, mostly cloudy, with a high near 25. Northwest wind 5 to 15 mph becoming west southwest in the afternoon. Chance of precipitation is 30%. Total daytime snow accumulation of less than one inch possible. Snow likely, mainly after 11pm. Cloudy, with a low around 18. South southwest wind 9 to 15 mph. Chance of precipitation is 70%. New snow accumulation of around an inch possible. A 50 percent chance of snow. Cloudy, with a high near 28. Northwest wind 8 to 13 mph. New snow accumulation of around an inch possible.
Temperatures: High 25 deg. F. Low 18 deg. F. High 28 deg. F.
Wind direction: NW becoming SW S/SW NW
Wind speed: 5-15 9-15 8-13
Expected snowfall: Less than 1 in. 1 in. 1 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.