THIS AVALANCHE ADVISORY EXPIRED ON February 17, 2020 @ 5:58 am
Avalanche Advisory published on February 16, 2020 @ 5:58 am
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard today is Considerable above 7,000 feet on slopes that are wind loaded and steeper than 30 degrees. Below 7,000 feet the Avalanche Hazard is Moderate. As we get more snow today along with Southwest winds upwards of 20 MPH, Natural avalanches are possible, and Human tiggered avalanches will become more likely. Buried surface hoar is preventing the upper 1-2 feet from bonding well.  

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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We have been finding some fragments of wind broken surface hoar, buried a little over a foot down from the snow surface, that was likely the culprit of a natural avalanche cycle that happened just towards the end of the last storm last weekend on North and East aspects. In out test pits throughout the advisory area this week, we have seen this layer producing moderate, broken failures in compression, and lacking the ability to propagate in extended column tests. 

Over the next 72 hours we will need to be cautious as we will be putting a new snow load on top of surface hoar that formed during this past weeks awesome clear nights. We may very well see some natural avalanches this weekend (Sunday-Monday) on this layer, and it may hang out and wait for a trigger like a snowmobile or skier in sheltered areas where the snow surface was protected from the Sun and wind this past week. 

Evaluate sheltered, steep slopes carefully this holiday weekend before committing to exposed, or big terrain. Buried surface hoar can be tricky, and when it propagates it can spread out fractures sometimes cross a whole ridgeline---we have to wait and see if this happens over the next 48 hours. Evaluate slopes carefully that are steep and protected, and definately spread out in steep terrain, use good safe travel protocols. We will be monitoring this problem closely over the next week.

Below is a photo of fresh Surface hoar at 7700 feet on a North aspect of Sgts Mountain Thursday afternoon.

Avalanche Problem 2: Wind Slab
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 Older slab problems have likely bonded and strengthened, but you may find some small fresh, shallow wind slabs today that formed Friday's from gusty northern winds on upper elevation exposed slopes. Above 7,000 feet is where you are most likely to find wind slabs, especially above 8,000 feet.  Watch out for red flags like cracks, or pillows, cornices, and wind scultpted snow. Idenifying theese features may be difficult today with fresh snow hiding the signs.

This afternoon we are forecasted to get some more snow and winds in the 20 MPH range which will likely form new wind slabs that could be reactive to the weight of a person, and possibly fail naturally today.

 

advisory discussion

Our annual fundraiser is this coming Friday, Februrary 21st at Banyons clubhouse on the McCall golf course. This year we will have a Silent Auction and Choose your own raffle prizes!  Live music by Jughandle Parade from 6-9!  Our goal this year is to raise $5000. which will go directly into additional forecasts for next season, our future forecasters scholarships and providing more Avalanche Awareness classes.  Tickets will be sold at the door.  $10.00 gets you in the doors with a raffle ticket.  Come on out and help make this years fundraiser this biggest yet!!

 

*Skiers and 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

Friday, we ski toured just South West of Hard Creek Meadows, North of Brundage Ski Resort. We observed about an inch of new snow in the form of graupel, and had a variety of snow coming down, mostly in the form of 2-3 mm graupel. There was still a lot of soft snow to be had on aspects that did not receive direct Sun.

  Southern aspects had a 1 inch crust underneath the inch of graupel.

 

Our test pit at 7,000 feet on a Northwest aspect again revealed a layer of buried surface hoar about a foot down from the surface. The structure was right side up, and compression tests failed moderately (CT14Q2-Q3, SC), but lacked propagation in an extended column test (ECTN) .

 MIT Pit on the buried surface hoar. Moderate shear strength.

 

 

 

 

 

 

 

 

 

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: 19 deg. F.
Max. temperature in the last 24 hours: 19 deg. F.
Average wind direction during the last 24 hours: N
Average wind speed during the last 24 hours: 6 mph
Maximum wind gust in the last 24 hours: 16 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

 

Area Forecast Discussion
National Weather Service Boise ID
300 AM MST Sun Feb 16 2020

.SHORT TERM...Main precipitation is now underway and will
continue through mid-morning in eastern Oregon, and early
afternoon in western Idaho when the storm`s cold front moves
through. The current winter weather advisory for the Idaho
mountains has been extended until 2 PM MST this afternoon.
Rain and snow will turn showery after the front passes and
end in most areas by sunset. Exceptions will be along the
ID/NV border where snow showers will continue until late
evening, and in the central Idaho Mountains where they will
continue through the night under the upper trough. Snow showers
will expand southward into the Boise Mountains Monday as the
upper trough axis moves through, ending Monday evening,
followed by clearing and colder. Today`s cold front will also
be followed by gusty northwest winds in the Snake Basin this
afternoon and early evening, strongest east of Mountain Home
where speeds will reach 25 mph with gusts to 40 mph. Elsewhere,
winds will be generally northwest 10-20 mph. Monday night
through Wednesday will be clear, dry, and cold, especially on
the Idaho side. Low temps Tuesday and Wednesday mornings will
be below zero in the Camas Prairie and other high basins in
Idaho. Not quite as cold on the Oregon side. Highs will be
in the 20s and 30s in the mountains, and upper 30s through 40s
in the valleys but the days will be sunny with only light winds.

.LONG TERM...Wednesday night through Sunday...Dry and seasonable,
with gradual warming through the week as high pressure dominates
the forecast. There is decent model agreement that the next
weather-maker will arrive over the weekend, with a good chance of
precipitation area-wide.

&&

.AVIATION...Widespread precipitation is expected through at least
18Z today. MVFR/IFR conditions along with terrain obscuration is
likely, especially over and around the mountains. Snow levels will
rise to 4000-4500 feet MSL overnight. Surface winds: variable 5-15
kts becoming west-northwest 10-20 kts this afternoon. Winds aloft
at 10k feet MSL: west-northwest 40-50 kts.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until 2 PM MST this afternoon
IDZ011-013-033.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Sunday Sunday Night Monday
Weather: Snow before 11am, then scattered snow showers after 11am. High near 34. Southwest wind 5 to 14 mph. Chance of precipitation is 90%. New snow accumulation of 1 to 3 inches possible. A 40 percent chance of snow showers after 11pm. Mostly cloudy, with a low around 18. West wind 8 to 13 mph becoming light and variable in the evening. New snow accumulation of less than one inch possible. A 50 percent chance of snow showers. Mostly cloudy, with a high near 29. Calm wind becoming west northwest around 6 mph in the afternoon. New snow accumulation of less than one inch possible.
Temperatures: 34 deg. F. 18 deg. F. 29 deg. F.
Wind direction: SW W WNW
Wind speed: 5-14 18-13 6
Expected snowfall: 1-3 in. Less than one in. Less than one in.
Granite Mountain at 7700 feet.
  Sunday Sunday Night Monday
Weather: Snow before 11am, then snow showers likely after 11am. Temperature falling to around 16 by 5pm. Wind chill values between zero and 10. Breezy, with a south southwest wind 13 to 21 mph. Chance of precipitation is 90%. New snow accumulation of 3 to 5 inches possible. Snow showers likely, mainly after 11pm. Mostly cloudy, with a low around 9. Wind chill values between -1 and -8. Breezy, with a west wind 15 to 20 mph becoming southwest 7 to 12 mph after midnight. Chance of precipitation is 70%. New snow accumulation of 1 to 3 inches possible. Snow showers. High near 16. Wind chill values between -2 and 4. Southwest wind around 9 mph becoming northwest in the afternoon. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.
Temperatures: 16 deg. F. 9 deg. F. 16 deg. F.
Wind direction: SSW W-SW SW-NW
Wind speed: 13-21 15-20 9
Expected snowfall: 3-5 in. 1-3 in. 1-3 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.