THIS AVALANCHE ADVISORY EXPIRED ON February 10, 2020 @ 7:16 am
Avalanche Advisory published on February 9, 2020 @ 7:16 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The Avalanche Hazard today is Considerable in the upper elevations where a combination of heavy snow accumulations and high 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 terrain. Cooling temperatures are helping to heal the new snow instabilities we have seen this week but avoiding steep or consequential terrain is still your best bet.

How to read the advisory


  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Winds accompanying the storms this week have been relatively light.  Wind speeds started to increase Friday night with gusts over 50 mph yesterday morning.  Shifting winds, cooler temperatures and another 6 inches of snow through the day yesterday have created even more potential for wind slabs today. The addition of wind slabs to our list of avalanche problems will rapidly increase the density of the slab and up the consequences of triggering an avalanche in wind affected terrain.  Avoid traveling near ridgelines, below cornices or in areas where you can see or feel a change in the surface or density of the snowpack.  Obvious clues like ripples, drifts, or cracks shooting out from your skis or sled mean you should move to more wind protected terrain.

Avalanche Problem 2: Storm Slab
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Local snotel sites picked up just shy of 4 inches of Snow Water Equivalent since Tuesday.  Brundage Mountain Resort is reporting 45 inches since Tuesday.  All of this adds up to a LOT of snow in a relatively short period of time.  Temperatures have been increasing steadily with this storm and the snow that was soft, cold and unconsolidated is turning into a warmer, more cohesive slab.  Increasing winds yesterday will add to the problem especially in the upper elevations.   A combination of crusts and weak layers made up of preserved surface hoar and near surface facets are underlying the new snow in many places allowing avalanches to propagate over larger areas.  The temperature variation from above freezing to high teens last night will help to help set up or heal the storm slab problem pretty quickly.  Given the potential size of the avalanche problem your best bet is to err on the side of caution today and give steep slopes in the mid and upper elevations another day or two to heal.

 

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

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

The northern portion of our advisory area picked up a little more snow yesterday with winds that were steady in the mid teens.  South valley picked up a bit of snow as well and saw substantially more wind through the day yesterday.   Today is shaping up to be a great day to be in the mountains with mostly sunny skies.  Winds will still be a factor today with gusts forecasted to 25mph.  Expect newly formed windslabs on a variety of upper elevation slopes.

Also, as a heads up, not all snowmobile trails have been groomed in the last few days.  The County Groomers are concentrating on the main routes and routes close to the popular parking areas.  Grooming out of the Titus lot stops at the Association Cabin meadow north of Goose Lake on the Goose Lake Rd.   Trail sleds and beginner riders will find conditions challenging in many places. If you see the County groomers or the Brundage Mt snow cats out on the roads, give them a thumbs up, they have been working hard this week!  Check out the most recent grooming updates by clicking here.

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: 12 deg. F.
Max. temperature in the last 24 hours: 20 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

.SHORT TERM...Today through Wednesday...An upper ridge centered
off the West coast will extend its influence over the interior
NW through the period. Much of the area will remain dry as storm
systems traversing the ridge will drop into the U.S east of the
Continental Divide. A slight chance of snow showers will extend
into eastern Valley county on Monday as a trough tracks through
MT, and again late Tue/Wed with another passing upper wave.
Locally breezy northwest winds today, increasing in scope on
Monday in response to the passing trough. Lighter terrain driven
winds will setup to finish the period. Temperatures will be near
normal through Wednesday.

.LONG TERM...Wednesday night through Saturday...Dry conditions
expected Thursday before a series of systems move through the
region bringing a threat of snow showers. The first one arrives
Thursday night/Friday morning but ECM/Canadian handle it slightly
different by indicating that is splits as it drives into the
PacNW. The GFS keeps it intact as it drops through the Great
Basin. In any case, a threat of showers is anticipated...more
across the mountains of Idaho. Less precip if it does in fact
split as it moves into the region. Models continue in good
agreement through the end of the weekend as yet another system
drops into the region in a northwest flow aloft. This would bring
another round of snow showers to the region. Temperatures expected
to remain at or slightly above normal through the period.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Sunday Sunday Night Monday
Weather: Sunny, with a high near 31. North northwest wind around 5 mph becoming calm. Partly cloudy, with a low around 14. Light and variable wind. Sunny, with a high near 32. Calm wind becoming northwest 5 to 9 mph in the afternoon.
Temperatures: 31 deg. F. 14 deg. F. 32 deg. F.
Wind direction: NNW Variable NW
Wind speed: 5 Light 5-9
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Sunday Sunday Night Monday
Weather: Sunny, with a high near 22. North northeast wind 7 to 10 mph, with gusts as high as 25 mph. Partly cloudy, with a low around 12. North wind around 7 mph Mostly sunny, with a high near 22. North wind 8 to 10 mph.
Temperatures: 22 deg. F. 12 deg. F. 22 deg. F.
Wind direction: NNE N N
Wind speed: 7-10, Gusts to 25 7 8-10
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.