Avalanche Advisory published on February 2, 2018 @ 7:01 am
Issued by -
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A moderate avalanche hazard exists above 6,000 feet due to freshly formed and lingering wind slabs. New snow and ridgetop winds have created fresh slabs and older slabs remain from last week's wind event. Warm temperatures have stabilized most of the lingering slabs, but isolated areas with sensitive wind slabs still exist. Travelers should avoid steep slopes with recent evidence of wind loading. Below 6,000 feet, the avalanche hazard 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: Wind Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Very Likely
  • Size ?
    Very Large

The past week provided a roller coaster of snowpack and avalanche conditions. Last weekend, heavy snowfall and winds created tender slabs that produced several avalanches and resulted in a partial burial. Warming temperatures stabilized many of the layers in the upper snowpack. Cold temperatures followed and left most of the zone with a melt/freeze crust at or just below the surface.

1-3 inches of new snow fell overnight. At uppper elevations, winds have been transporting snow and forming new wind slabs. Skiers and riders should look for signs of recent loading and should pay additional attention to lingering wind slabs that formed during last week's wind events. These slabs may be found in steep terrain near ridges or exposed areas and may be large enough to injure and bury a person. 

advisory discussion

SHORT TERM...Today through Saturday...An exiting upper trough
will keep showers across the e-central Oregon and w-central Idaho
mountains through mid-morning. The break in precipitation is brief
as another wave drops into central Idaho tonight. It will follow
a similar path as recent systems, keeping the focus of light
rain/snow across Baker county Oregon and the central Idaho
mountains. The Snake Plain will remain on the southern edge of
precipitation chances overnight. Light showers continue in the
central Idaho mountains on Saturday with the passage of another
weak wave. Snow accumulation will be light (up to 2 inches) and
limited to areas above 6500 feet through Saturday. Southeast
Oregon, much of the Snake Plain and far southwest Idaho will
remain dry through Saturday with periods of cloud cover the
passage of each upper wave. Temperatures are mild, running 10-15
degrees above normal.

.LONG TERM...Saturday night through Thursday...A ridge of high
pressure lingers offshore through the long term forecast. A
series of waves will pass up and over this ridge with most of the
shower activity staying in our northern zones. There is a slight
chance Monday afternoon to see some showers push a little further
south. Tuesday onward precipitation will be limited to the central
Idaho mountains. Snow levels sit at or above 6k feet MSL through
the majority of the period meaning snow will be limited to the
highest elevations. Above normal temperatures are expected through
the entire period.

recent observations

Yesterday, we toured in the Lick Creek Summit area near Beaverdam Peak. Wind effected snow was present near ridges and in exposed areas. We found a pronounced melt/freeze layer close to the surface in most areas. Within the snowpack, several burried melt/freeze layers exist 40 to 100 cm below the surface from past warming events and/or rain. Snow stability tests on these layers demonstrated little to no results.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 25 deg. F.
Max. temperature in the last 24 hours: 25 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 3 mph
Maximum wind gust in the last 24 hours: 20 mph
New snowfall in the last 24 hours: 3 inches
Total snow depth: 62 inches
Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Rain and snow before 11am, then a chance of rain. High near 39. South wind around 6 mph becoming calm. Chance of precipitation is 100%. Little or no snow accumulation expected. Rain likely, mainly before 11pm. Mostly cloudy, with a low around 32. South southwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 70%. Snow likely before 11am, then rain and snow likely. Cloudy, with a high near 39. Light south southwest wind. Chance of precipitation is 70%. Little or no snow accumulation expected.
Temperatures: 39 deg. F. 32 deg. F. 39 deg. F.
Wind direction: South South Southwest South Southwest
Wind speed: 0-6 mph 0-5 mph Light
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Snow. High near 36. South southwest wind around 14 mph, with gusts as high as 20 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 1 to 2 inches possible. Rain and snow likely before 11pm, then a chance of snow. Mostly cloudy, with a low around 31. Southwest wind 9 to 13 mph. Chance of precipitation is 70%. New snow accumulation of 1 to 2 inches possible. Snow likely. Mostly cloudy, with a high near 36. Southwest wind 8 to 13 mph. Chance of precipitation is 70%. New snow accumulation of around an inch possible.
Temperatures: 36 deg. F. 31 deg. F. 36 deg. F.
Wind direction: South Southwest Southwest Southwest
Wind speed: 9-14, gusts to 20 mph 9-13 mph 8-13 mph
Expected snowfall: 1-2 in. 1-2 in. 0-1 in.

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.