Avalanche Advisory published on March 3, 2017 @ 6:38 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The Avalanche Danger is Moderate on upper elevation wind exposed slopes where wind slabs continue to form and on slopes that receive direct sun throughout the day.  Wet, loose avalanches may be possible if Southerly slopes are exposed to direct sunlight.  Expect this problem to begin early on East facing slopes and move around the bottom of the compass throughout the day.  Below 7000 feet on protected slopes the danger 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: Loose Wet
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Very Likely
  • Size ?
    Very Large

The combination of warming temperatures and direct sunlight may be enough to tip the scale on some of the cold snow that can be still be found on most aspects.  Yesterday,  cooling winds and partly cloudy skies kept the snow pack fairly cool until late in the afternoon.  If the sun makes a prolonged appearance today, you can expect that steep solar aspects will begin shedding some snow.  Rocky areas and upper elevation East facing slopes will need to be watched in the first half of the day with the avalanche problem migrating around the South half of the compass to West facing slopes in the afternoon.  This is an easy problem to avoid, if you notice increasing roller ball activity or trees shedding snow, move to a cooler aspect.

Avalanche Problem 2: Wind Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Very Likely
  • Size ?
    Very Large

Winds over the last week have had no problem moving the light, dry snow around throughout the upper elevation terrain. South Valley areas saw higher winds earlier this week than the Northern Mountains.  Over the last 48 hours winds have been out of the W and SW for the most part and high enough to continue to move available snow.  The windward aspects are now pretty much sculpted and stripped of most of the available snow but higher Southwest winds today will continue to transport whatever loose snow is left.  

Cornices as well as the skiing and riding conditions are "all time" right now.  Avoid traveling near these monsters or lingering on slopes below them.  Over the next few days cornices will likely be sending large pieces downhill as warmer snow and high winds overload them.  Winds ahead of the next storm system will strengthen throughout the day with gusts over 30 today and as high as 47 MPH tonight. Warm snow and high winds will make for some new avalanche problems tomorrow and through the weekend.

advisory discussion

Snowmobiler/Snowbiker Travel Restrictions: Please respect these closures and other users recreating in them.  Winter Travel Map(East side). You can download the map to the AVENZA app on your phone, and know your exact location while you are out riding.  It is your responsiblity to know where closures exist on the forest.

The Granite Mountain Area Closure is in effect Jan15-March 31, please respect Snowcats operating in this and nearby areas.  In addition there are other areas on the Payette National Forest that are CLOSED to snowmobile traffic including Jughandle Mt east of Jug Meadows, North of Boulder Mtn, East of Rapid Peak, North of the 20 mile drainage, Lick Creek/Lake Fork Drainage (on the right side of the road as you are traveling up canyon), and the area north of Brundage Mt Ski area to junction "V" and along the east side of Brundage and Sergeants' Mts. with the exception of the Lookout Rd( junction "S").

The Friends of the Payette Avalanche Center (FPAC) needs YOU! We are in desperate need of more user support and financial assistance. The avalanche forecast is not a guaranteed service, and is in jeopardy of dwindling down to only a couple of days a week in the near future.We have equipment that is overdue for replacement but lack the funds to purchase new gear including weather station parts and our forecast sleds.  Please help if you can by clicking the DONATE tab above. If you value this life saving information, make a donation or help the FPAC in raising funds for the future.

recent observations

Yesterday we traveled through some deep, protected areas and some stiff wind scoured areas on the ridgelines.  Moderate winds were easily transporting the remaining available snow into the Northerly aspects.  Tree wells and wind drifts are very large right now as are the cornices on multiple aspects.  The cold, blower snow has begun to consolidate and is traveling much shallower than it was early this week.  Boot penetration has gone from over thigh deep to just about knee deep this week.  It has not gotten warm enough to form slabs in wind protected areas but upper elevation slopes definitely have begun to solidify where the combined efforts of the sun and wind have begun creating a more cohesive layer.  Sledding was all time again yesterday and skiing was still great in the protected areas.  If you missed out on the snow this week, then you missed it.  Conditions were light and deep and completely atypical for the West Central Mountains. 

NW facing ridgeline above French Creek showing large cornice formation and scouring on ridgetops. 3/2/17

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 20 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: 5 mph
Maximum wind gust in the last 24 hours: 15 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 59 inches

SHORT TERM...Today through Saturday...Dry conditions will start off
the forecast period. Mid to high level clouds continue to stream
across the forecast area, with otherwise quiet conditions. An
approaching Pacific low pressure system will send a decent moisture
push across the area today. Snowfall will start across eastern
Oregon during the afternoon, and will spread into southwestern Idaho
during the evening hours. As the moisture and front progress
eastward, resulting snowfall looks to anchor over the west central
mountains of Idaho, lingering through at least Saturday where it may
produce 2 to 6 inches of snowfall over the higher peaks. However,
much of the area is anticipated to see some form of precipitation,
except portions of southern Twin Falls county which may remain dry.
The best snowfall looks to occur tonight and through Saturday,
though periods of rain or light snowfall will be found outside of
this window. Snow levels across the area remain around 4500 ft
through the bulk of initial precipitation, keeping some areas as a
rain or rain-snow mix. For now, no winter weather products will be
hoisted, though one last look will occur tomorrow for any model
changes to tip the scales in the other direction, especially for the
the west-central mountains of Idaho. Roadways, especially Highway 95
through Adams county may see some adverse impacts from snowfall
beginning tonight.

LONG TERM...Saturday night through Thursday...A strong cold front
begins to push into SE OR by late Saturday and SW ID by early Sunday
morning. Strong southwest winds aloft will keep the heaviest
precipitation up in the West Central and Boise Mountains with
scattered snow showers in the lower valleys. Snow levels will start
off around 5000 feet MSL then plummet down to valley floors with
the passage of this cold front by Sunday afternoon. Chances of snow
showers remain through Tuesday evening. After Tuesday, snow levels
begin to climb once again remaining above 4500 feet MSL through the
rest of the period. Differences in models after Wednesday leave
timing of the next systems difficult to pin down, but left the
mention of precipitation in the forecast for the time being.
Temperatures will be below normal through Tuesday then above normal
for the remainder of the extended.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Mostly cloudy, with a high near 38. South wind 6 to 10 mph Rain and snow likely before 11pm, then snow. Low around 31. South wind 10 to 15 mph. Chance of precipitation is 90%. New snow accumulation of 1 to 2 inches possible. Snow showers. High near 38. South wind around 11 mph. Chance of precipitation is 100%. New snow accumulation of around an inch possible.
Temperatures: 38 deg. F. 31 deg. F. 38 deg. F.
Wind direction: S S S
Wind speed: 6-10 10-15 11
Expected snowfall: 0 in. 1-2 in. 1 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Mostly cloudy, with a high near 29. Breezy, with a south southwest wind 18 to 23 mph, with gusts as high as 32 mph. Snow likely. Cloudy, with a low around 23. Windy, with a south southwest wind 30 to 34 mph, with gusts as high as 47 mph. Chance of precipitation is 70%. New snow accumulation of 4 to 8 inches possible. Snow showers. High near 27. Breezy, with a south southwest wind 22 to 24 mph. Chance of precipitation is 90%. New snow accumulation of 5 to 9 inches possible.
Temperatures: 29 deg. F. 23 deg. F. 27 deg. F.
Wind direction: SW SSW SSW
Wind speed: 18-23, gusts to 32 30-3, gusts to 47 22-24
Expected snowfall: 0 in. 4-8 in. 5-9 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.