THIS AVALANCHE ADVISORY EXPIRED ON January 6, 2018 @ 7:16 am
Avalanche Advisory published on January 5, 2018 @ 7:16 am
Issued by Jess Asmussen - Payette Avalanche Center
bottom line

Moderate avalanche danger exists today at mid and upper elevations due to persistent slabs that exist above the buried Thanksgiving rain crust. A secondary problem, wind slabs, can be found near ridges and other exposed areas. While these slabs may be difficult to trigger, the shallow snowpack and numerous obstacles will increase the consequences if you are caught in an avalanche. The safest terrain (and arguably best snow quality) can be found in low angled, sheltered areas. 

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Persistent Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

A persistent weak layer (45-60 cm from the surface) can be found just above the hard Thanksgiving rain crust. This layer doesn’t exist everywhere, but can be found in most mid to upper elevation areas. Failures in this layer may be difficult to initiate, but human triggered avalanches are possible. This layer is fairly continuous throughout many areas, and avalanches could be large enough to injure or bury a person.

Yesterday in the Fisher Creek Saddle area (8100 feet, NE aspect), snow stability tests were failing and propagating with clean, fast shear qualities – ECTP 23 and PST 40/100 (End) (see video). Observers in the Jughandle Mountain area and Lick Creek area have noted similar results with clean shears and propagation during their tests.

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

Wind slabs are present near ridges and in exposed areas all across the forecast area. The wind slabs are shallow (less than 20 cm) and have been reactive to ski cuts. They are unlikely to bury a person, but they may push you into obstacles, or worse, trigger the deeper persistent slab below. Common signs of wind slabs are drifted, textured, hollow snow. 

recent observations

Yesterday in the Fisher Creek Saddle area, north of Brundage Mountain, we found a mix of conditions. The persistent slab was found on most aspects and elevations. Gusty winds over the last week have created wind slabs at and near the ridgelines. Warm temperatures and sunny skies have begun to create sun crust on solar aspects. Overall, good skiing and riding conditions can still be found at the upper elevations. Lower elevations have a thin snowpack, with lots of rocks and stumps still present.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 28 deg. F.
Max. temperature in the last 24 hours: 36 deg. F.
Average wind direction during the last 24 hours: 169
Average wind speed during the last 24 hours: 4 mph
Maximum wind gust in the last 24 hours: 15 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 69 inches
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.