THIS AVALANCHE ADVISORY EXPIRED ON January 21, 2017 @ 5:39 am
Avalanche Advisory published on January 20, 2017 @ 5:39 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The avalanche danger is CONSIDERABLE above 6000 feet.. Our most recent storm cycle put down 18-21 inches of new snow that fell on a variety of old snow surfaces including well developed Surface Hoar, Near Surface facets and firm crusts.  In addtion, a fresh crop of wind slabs will be found near the ridge tops on leeward slopes. Small to medium sized, human triggered avalanches are likely today.

How to read the advisory


  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Persistent Slab
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A relatively widespread layer of Surface Hoar and Near Surface Facets is now lying below the new snow.  We found this layer yesterday 15-18 inches down in the middle elevations and in higher areas that were protected from the winds that accompanied this last storm cycle. Surface Hoar and faceted snow layers are responsible for more avalanche accidents and fatalities than all other types of avalanches combined.  This layer failed in many steep areas naturally as the new snow came in but is waiting for a trigger in many more.  This is a very tricky layer to predict or forecast for due to the variability and the uncertainty of where you will find it in the snowpack and throughout the mountains right now.  The only way you will know for sure is to dig in to the snow and look for the obvious grey line in the snow.  Whumphing or collapsing of the snowpack will let you know that you are in an area with buried surface hoar or faceted snow.  With this kind of variability, you will need to dig in lots of places as you travel.  Hand pits in lots of locations or 5 minutes with your shovel could save your life today.

The photos show one of the many small avalanches we saw yesterday along the Goose Creek Rd and a close up of the surface hoar layer at the height of the saw.  This type of problem tends to linger for awhile and the slab above it will probably be even more touchy today with cooler temperatures overnight last night.

 

                                   

 

 

Avalanche Problem 2: Wind Slab
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A fresh crop of wind slabs was created in the upper elevations with the last storm cycle and winds in the upper 20 mph range common throughout most of the area.  The winds have swirled across the bottom of the compass from East to South West creating the possibility of 1-3 foot deep wind slabs on the northern portion of the compass as well as East and West aspects.  These slabs may be resting on old wind slabs, a layer of surface hoar, or other faceted (loose grained) snow or on firm crusts.  Pay attention to the obvious signs of wind affected snow, rounded, sculpted, drifted or pillowy looking snow will let you know right where the wind deposited snow piled up.  Hollow sounding or feeling snow should tell you to find a different slope as well.

 

Photo showing large wind drifts across the Goose Lake Rd near Hazard Campground yesterday.

 

advisory discussion

Snowmobiler/Snowbiker Travel Restrictions:  a quick reminder that the Granite Mountain Area Closure is now in effect.  In addition there are other areas on the Payette National Forest that are CLOSED to snowmobile traffic including Jughandle Mt east of Jug Meadows, 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 snd Sargeant's Mts. with the exception of the Lookout Rd( junction "S").  Please respect these closures and other users recreating in them.  Winter Travel Map(East side)

Remember your information can save lives. If you see anything we should know about, please participate in the creation of our own community avalanche advisory by submitting snow and avalanche conditions. It's okay if you leave some fields blank, just fill out what you know and/or submit photos. You can  also email us at  forecast@payetteavalanche.org.

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. 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.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 19 deg. F.
Max. temperature in the last 24 hours: 26 deg. F.
Average wind direction during the last 24 hours: WSW
Average wind speed during the last 24 hours: 7-10 mph
Maximum wind gust in the last 24 hours: 28 mph
New snowfall in the last 24 hours: inches
Total snow depth: 80 inches
weather

.SHORT TERM...Today through Saturday...Areas of dense fog (with visibilities of a quarter mile or less) will continue this morning in the lower valleys.  The fog is expected to dissipate by late morning. An upper trough near the coast will direct precipitation into SE Oregon this morning and SW Idaho late this afternoon and evening. Latest models continue with the trend of slightly warmer temperatures and slightly higher snow levels through Saturday. Therefore, will adjust both of these weather parameters accordingly. The slightly warmer temps and higher snow levels will lead to the possibility of rain with the snow in Upper Treasure Valley, where snow levels will average 2500-3000 feet tonight through Sunday. Snow accumulations are possible in the Upper Treasure and Western Magic Valleys, but total amounts are expected to be less than an inch. .

LONG TERM...Saturday night through Thursday...Active weather pattern still on track through Tuesday. An upper level low off the Pacific Northwest coast Saturday night will slowly shift east through Monday night. Best chance of precipitation will be Sunday as a moist southwesterly flow develops over the area ahead of the approaching upper level low. As with the previous weather systems, snow level will be tricky, but still looking like most locations will see snow, but there could be a change to at least a rain/snow mix in the lower valleys by Sunday afternoon. As the upper level low gets closer to the region, snow levels will once again fall to valley floors. Models do not seem to have a good handle on how much precipitation we will see with this latest storm but still thinking 2-4" in the valleys and 4-6" in the mountains. Upper level low will move over the forecast area Tuesday with decreasing precipitation. Wednesday and Thursday an upper level ridge develops over the area with a cold northerly flow and increasing chance of valley inversion developing.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: AM Patchy fog, then mostly cloudy. Cloudy with a 40% chance of snow. Cloudy with a 30% chance of snow.
Temperatures: 32 deg. F. 22 deg. F. deg. F.
Wind direction: ESE SE S
Wind speed: 3-6 3-5 3-5
Expected snowfall: 0 in. less than 1/2 in. less than 1 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Cloudy Cloudy with a 40% chance of snow Cloudy with a40% chance of snow
Temperatures: 29 deg. F. 21 deg. F. 27 deg. F.
Wind direction: SSE S SSW
Wind speed: 14-18 13-18 11-13
Expected snowfall: 0 in. less than 1 in. around 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.