THIS AVALANCHE ADVISORY EXPIRED ON February 11, 2020 @ 7:28 am
Avalanche Advisory published on February 10, 2020 @ 7:28 am
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard today is Moderate in the mid and upper elevations where winds have created wind slabs that may be overlying crusts or buried weak layers.  Human caused avalanches 1-4 feet deep remain possible on all steep wind loaded terrain. Cornices are large,have sensitive edges, and overhanging. The Sun may produce small natural point release avalanches during the day

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
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As the Sun heats up the snow surface today, we will see some small, loose wet avalanche activity on slopes getting direct Sun, especially around rocks. You might be able to get some snow moving easier on steep solar effected slopes, so pay attention to the aspect and move to cooler slopes that are not getting direct sunlight.

Avalanche Problem 2: Wind Slab
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Winds have been doing a great job of moving the snow during this last storm cycle in just about every direction. During most of the wind activity, we saw some pretty warm temperatures. Since yesterday, we have been under a colder northern flow with pretty light winds. Any wind slab problems that you may encounter are going to be older, and probably not going to be very large. The colder temps should be helping the stiffer snow to bond.  

The ridges are holding some very large cornices that are overhanging a lot in some areas. Yesterday, on an East aspect in the Lick Cr drainage I was able to walk along and kick the cornices with my skis, easily breaking off the outer couple feet...staying localized to where I kicked, but failing pretty easily given their lack of support, overhanging. Give the ridge lines respect and stay back far from their edges. 

 

Avalanche Problem 3: Persistent Slab
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A combination of weak layers was distributed last week and at the beginning of this week.  Melt freeze and sun crusts from last week's warmup followed by a 20 degree cool down formed on lower elevation slopes and slopes that got hit by the sun last week.  In addition,  a thin layer of surface hoar and near surface facets formed during the very cold, clear weather that followed the warmup. 

We found some evidence of preserved surface hoar earlier this week in our pits.  Given the warm temperatures that we have seen up to last night and the amount of snow sitting above these layers,  it is becoming more unlikely you will trigger an avalanche in these layers...but it is still possible in the middle and upper elevation areas where temperatures remained cooler Thursday and Friday.  

A snowmobiler triggered an avalanche that likely failed on a layer of surface hoar in the Twin Lakes area Thursday that also was able to propagate around several small ridges and knobs. See the observation and description he posted on our recent observation page.

With over 3 feet of snow, this problem has likely gotten crushed. Yesterday, We were able to get hard results (CT30 RP) on fragments of surface hoar over 4 feet down, that we could barley pick out under a hand lens.

advisory discussion

*Snowmobiliers, the Granite Mountain closure went is in effect from January 15-March 31. Please respect Brundage Catski terrain closures which are CLEARLY marked on the west side of Goose Lake.  There is a shared use route at the northern end of the closure to allow access to Granite Mt Lookout and the upper east face of Granite Mt.  Additionally, public motorized use of ANY other Catski road is not permitted, including the roads between Brundage Reservoir and the East side of the Goose Lake Road in the Slab Butte and 76 areas. Please respect closed roads and areas and only ride on open roads and in open terrain.  There are also other areas that are closed to snowmobiling in the West Central Mountains. Click here for the Payette National Forest Winter Travel Map.

*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 traffi

recent observations

Yesterday, we ski toured in the Lick Creeck drainage near the Lick Cr summit yurts. Test pits revealed a moderately strong snowpack. Ridgelines were riddled with massive cornices that were senistive to skis, and broke easily. The trail breaking was a bit chalenging in the deep snow conditins with a punchy denser layer a foot down that supported a skier in some places. Steeper slopes were still providing better skiing with the deeper, upside down layer. buried a foot beneth light denisty snow on the surface. Any large avalanches that released during the storm were mostly erased. We did see some evidence of crowns that were barley visible after the latest snow. We saw some small point release, solar activity under sunny blue skies. 

 

If you are out in the mountains and see recent avalanches, please take advantage of the good visibility and snap a picture to submit on our Observations page.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 15 deg. F.
Max. temperature in the last 24 hours: 27 deg. F.
Average wind direction during the last 24 hours: Offline
Average wind speed during the last 24 hours: NA mph
Maximum wind gust in the last 24 hours: NA mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

Area Forecast Discussion
National Weather Service Boise ID
251 AM MST Mon Feb 10 2020

.SHORT TERM...Today through Thursday...Mostly dry conditions
continue today under northerly flow. A bit of moisture within the
flow may introduce isolated showers across eastern Valley county
this afternoon. High pressure will keep quiet conditions through
Tuesday night. Late Tuesday night, moisture will move across
central Idaho and eastern Oregon, bringing a slight chance of
snowfall across the West Central Mountains of Idaho, and the
higher terrain of Baker county, Oregon through Wednesday morning.
Dry conditions expected by the early afternoon hours. Models in
decent agreement with a trough sending a slightly stronger push
of moisture towards the area on Thursday afternoon. Moisture
associated with this trough will reach into the forecast area
early Thursday morning, and will spread to include most of the
forecast area by Thursday afternoon. Snow levels of 2500 to 3500
ft expected by Thursday afternoon, allowing mountain snow with a
rain-snow mix in the valleys.

.LONG TERM...Thursday night through Monday...Models continue in
excellent agreement in showing a series of systems moving through
the region through the weekend. The first expected Friday morning,
which the ECM/Canadian still split the system as it moves into
the region but GFS keeps it intact. In either case, a threat of
rain/snow showers, stronger threat in the mountain region, are
possible. A much wetter system, which may have a decent tropical
connection, moves into the PacNW Saturday night/Sunday morning.
Snow levels will remain near the valley floors across the area. At
this time, models PWAT values around the 70-80 percentile which
gives the potential for decent precip amounts. Yet a third system
drops into the PacNw Monday. Temperatures expected to remain near
normal through the period.

&&

.AVIATION...VFR. Areas of MVFR/IFR conditions due to low
stratus spreading into the KJER area, and potentially KMUO from the
east prior to sunrise. Variable surface winds less than 10 kts
except 10 to 15 kts near KTWF through the day. Winds aloft near
10KFT north 25 to 40 kts, becoming 15 to 30 kts aft 10/18z.

 

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: Sunny, with a high near 32. Light north wind becoming northwest 6 to 11 mph in the afternoon. Mostly clear, with a low around 12. North northwest wind 5 to 7 mph becoming calm in the evening. Mostly sunny, with a high near 30. Light south wind.
Temperatures: 32 deg. F. 12 deg. F. 30 deg. F.
Wind direction: N North becoming calm S
Wind speed: 6-11 5-7 Light
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: Mostly sunny, with a high near 20. North northwest wind 9 to 13 mph. Mostly clear, with a low around 11. Calm wind becoming southwest 5 to 9 mph after midnight. Mostly sunny, with a high near 22. Southwest wind 6 to 8 mph.
Temperatures: 20 deg. F. 11 deg. F. 22 deg. F.
Wind direction: NW Calm becoming SW SW
Wind speed: 9-13 5-9 6-8
Expected snowfall: 0 in. 0 in. 0 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.