THIS AVALANCHE ADVISORY EXPIRED ON January 25, 2020 @ 6:51 am
Avalanche Advisory published on January 24, 2020 @ 6:51 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The Avalanche Danger is MODERATE. Natural avalanches are unlikely today but human triggered avalanches remain possible.  Shallow wind slabs are possible  on wind loaded or leeward slopes. You may also be able to trigger deeper avalanches on several other layers in the snow pack.  These layers will be most sensitive on slopes with a thinner snowpack.  Rain in the lower elevations may increase the potential for wet avalanches through the weekend.

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
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Wet snow and increasing wind speeds today will make the formation of new wind slabs possible on leeward slopes.  Yesterday we found a snowpack that was strengthening with only shallow instabilities so overall the snowpack is looking a lot better than it has all season.  The storm that will move into the area today and through the weekend will change that again.  Warm temperatures, increasing snowfall and winds gusting into the 30 mph range will add new wind slabs on wind affected terrain.  Pay attention to changing conditions as you change terrain.  There is still a fair amount of variability in the snowpack throughout the West Central Mountains and surrounding areas.

Avalanche Problem 2: Deep Slab
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Our deep slab problem right now is the perfect definition of  a LOW PROBABILITY/HIGH CONSEQUENCE scenario.  The chance of triggering is low and becoming more and more isolated but still lingering.  Upper elevation slopes where early season snow was preserved is your likely best culprit.  Add uneven rocky terrain into the picture and you are increasing the chance of finding that landmine trigger point where the snow is more shallow and the weak layer is closer to the surface.  The size and density of the slab and the potential outcome of triggering one of these deep, persistent slabs is enough to keep savvy riders and skiers off of and away from the likely slopes.  These are the same layers that have been responsible for fatalities near the West Central Mountains and in several other areas this winter.  We also saw several large, natural avalanches last week that released in these layers, so under the right conditions large avalanches are still possible.

We have been finding a well preserved layer of surface hoar 5 feet down in the snow pack on high, north facing slopes.  In addition loose depth hoar and facets are still present in some areas above and below the November crust that is now buried 7-8 feet down.  We generally do not see problem layers like these persisting with a deep snow pack above them in this area.  Variability throughout the surrounding area means that you may be riding or skiing in an area with 8 feet of snow one day and in areas with half that much the next day.   

The chance of rain in the lower elevations combined with heavy, wet snow and wind loading is going to give these layers another test this weekend.  Your best bet is to choose slopes with low consequences while the snowpack is adjusting to these changes. 

advisory discussion

Note to skiers accessing Jughandle Mountain from Silver Fox Trail.  Please park in signed areas only. Blocking or narrowing the road could result in loss of access to this area, ticketing or towing by Valley County.  There is NO parking allowed on the East side of the road or in the snowplow turnaround.  If you can't park in the signed area, park further down the road in a place where you are not obstructing traffic.

recent observations

Yesterday we toured into the Boulder Backcountry and found a mostly deep and stable snowpack with some lingering instabilities near the surface.  A mixture of grauple and wind affected snow failed in our pit tests around 30 cm or 8-12 inches down in the snowpack.  With snow depths getting close to 3m/9ft we didn't look for early season layers in this zone.  Coverage is looking great and even the lower elevation access is improving a lot.  Visibility proved to be the limiting factor with a freezing fog layer adding a little noisy but thin and manageable humidity crust to the surface of the soft snow.

Notice the depth of the probe in the pit! That is a 3 meter probe. It is getting deep out there.

   

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 27 deg. F.
Max. temperature in the last 24 hours: 28 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 5 mph
Maximum wind gust in the last 24 hours: 8 mph
New snowfall in the last 24 hours: 1 inches
Total snow depth: NA inches
weather

.SHORT TERM...Today through Monday...Solid band of pcpn moved
across eastern Oregon during the night and across the OR/ID
border around 2 AM MST on its way into western Idaho. Rain
and mountain snow will spread across all Idaho zones this
morning with snow level near 5400 feet in Baker County and
the west-central Idaho mountains, 6000 feet in south-central
Idaho, and 6800 feet in southeast Oregon. Pcpn will decrease
before noon in eastern Oregon, southwestern Idaho late morning,
and south-central Idaho early this afternoon. Pcpn amounts
will be generally .20 to .30 inch liquid. Drying and slightly
cooler tonight but another weaker surge of Pacific moisture
will bring more light rain and snow to eastern Oregon and the
west-central Idaho mountains Saturday, followed quickly by
heavier pcpn (.15 to .30 inch liquid) Saturday night, spreading
over all zones early Sunday morning, with snow level again
ranging from 5000 feet north to 6000-6500 feet near the
ID/NV border and 7000 feet along the OR/NV border. Clearing
in eastern Oregon Sunday afternoon, and western Idaho early
Sunday evening. Next surge of lighter pcpn will spread
across northern areas Monday. Temperatures will be generally
5 to 10 degrees above normal through the period, coolest on
Monday.

.LONG TERM...Monday night through Friday...An active pattern
will remain over the Pacific Northwest with a series of systems
pushing through the area. Snow levels will begin between 3500
and 4000 feet MSL before climbing above 5000 feet MSL by the
end of the period. Models remain in decent agreement for timing
and location of precipitation with the central Idaho mountains
expected to see the most activity. Valley locations will see
slight chances of rain through Thursday night before activity
becomes confined to higher elevations of central Idaho.
Temperatures will remain above normal for this time of year

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, mainly before 11am. Areas of fog before 11am. Snow level 5200 feet. High near 35. Southeast wind around 5 mph becoming calm in the morning. Chance of precipitation is 100%. Total daytime snow accumulation of less than a half inch possible. A 20 percent chance of snow. Areas of fog. Otherwise, mostly cloudy, with a low around 28. Calm wind. A 40 percent chance of snow. Areas of fog before 11am. Otherwise, cloudy, with a high near 34. Light southeast wind. New snow accumulation of less than a half inch possible.
Temperatures: 35 deg. F. 28 deg. F. 34 deg. F.
Wind direction: SE Calm SE
Wind speed: 5 Calm light
Expected snowfall: Trace in. 0 in. Trace in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Snow. Temperature falling to around 23 by 5pm. South wind 9 to 15 mph. Chance of precipitation is 100%. Total daytime snow accumulation of 3 to 5 inches possible. A 30 percent chance of snow, mainly after 11pm. Mostly cloudy, with a low around 20. South wind 6 to 9 mph. New snow accumulation of less than a half inch possible. A 50 percent chance of snow. Cloudy, with a high near 25. South wind 10 to 15 mph. New snow accumulation of 1 to 2 inches possible.
Temperatures: 23 deg. F. 20 deg. F. 25 deg. F.
Wind direction: S S S
Wind speed: 9-15 6-9 10-15
Expected snowfall: 3-5 in. Trace in. 1-2 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.