Avalanche Advisory published on March 21, 2017 @ 6:11 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The Avalanche Danger is Moderate today at all elevations and aspects.  Human triggered loose, wet avalanches remain possible on all steep slopes.  On leeward facing slopes in the highest elevations, you may encounter thin wind slabs that are reactive to the weight of a skier or snowmobile.   Cornice failures are also a major concern,  large cornices are verhanging ridge lines much farther than you might expect.  Avoid traveling near the edges of and spending time below heavily corniced ridgelines.

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 PAC and many of the neighboring Avalanche Centers are all starting to sound like broken records. With unseasonably warm temperatures and a pile of liquid precipitation over the last 10 days, wet slides and a melting snowpack are our main concerns. Temperatures actually rose overnight and the rain/snow line will be rising to over 8000 feet today.  With the lack of freezing temperatures, you run a good chance of starting a loose wet avalanche in pretty much any steep terrain.  With a series of crusts buried deep in our snow pack, the potential for deep, wet slab avalanches is lurking in our snow pack as well.  Tonight looks like a potential cool down with low temperatures below freezing in the forecast, but until our snow pack sees a hard freeze, you should avoid steep slopes especially those with terrain traps, gullies or bad consequences if your trigger a wet slide.

Cornices are a serious concern right now as well, if you are up high near ridge lines, yo can see monster cornices on pretty much all of the leeward slopes.  Avoid travel on or near corniced ridge lines and limit the amount of time you spend on slopes below them as well.


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

Winds have been whipping up high for the last few days.  While not a lot of snow has been available for transport recently, a few more inches of upper elevation snow fell Sunday and at the highest elevations yesterday. With temperatures rising to near 40 at 8200 feet today, any remaining wind slabs should be consolidated pretty well, especially with a significant cool down forecasted for tonight and through the end of the week.

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 responsibility to know where closures exist on the forest.

The Granite Mountain Area Closure is in effect Jan15-March 31, please respect Snowcats operating, signed and unsigned closures and other users 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").  

Ski areas are closed to snowmobile traffic, last week a group of snowmobilers poached the Northern portion of Tamarack Resort crossing under a fixed and signed rope line and left trenches on 3 of the ski runs that don't get groomed. Don't be "that guy" that gives sledders a bad name, please respect boundaries, snowmobiling at a ski resort is a low blow and a safety concern.

recent observations

No new avalanches were reported or observed, skiing the last few days has been a mushy, slushy, sometimes enjoyable, mostly sticky mess.  Warm temps have turned the upper snowpack into something that resembles a melting snowcone.

The image below is the 24 hour temp graph for Granite Mountain Wx station at 7600 ft.

Check out this table for Brundage Reservoir Snotel, precip gain and loss in last 30 days is impressive.  Also note the change in the amount of SWE.



CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 36 deg. F.
Max. temperature in the last 24 hours: 36 deg. F.
Average wind direction during the last 24 hours: SSE
Average wind speed during the last 24 hours: 7 mph
Maximum wind gust in the last 24 hours: 22 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches

SHORT TERM...Today through Wednesday...Moist southwest flow aloft
is still with us, bringing moisture off the Pacific and also,
importantly, a shortwave trough that will enhance convective
potential later today. A broad atmospheric river, or pineapple
express if you prefer, is oriented from the tropics northeast to
California this morning, and will provide plenty of moisture. The
aforementioned shortwave trough will bring lift and an increase in
instability, along with a cold front, to set the stage for what
could be a stormy second day of Spring. CAPE values are forecast
to be around 400 this afternoon, with 0-3km SREF over 150,
sufficient to allow a few storms to organize well enough to have
weak rotation. Although the main expected mode of convection is
linear, it would not surprise me to see a few cells organize well
enough to separate and become strong. Even any lines that form
will be capable of gusts to 45 mph as they move northeast at 25-30
mph. We expect mainly showers to develop this morning as the
shortwave approaches, with thunderstorms developing this afternoon
and moving rapidly from southwest to northeast across much of the
CWA. Temps will be tricky, as the highs for the day will depend
greatly on where the heaviest and longest-lasting showers develop
this morning, and where the earliest thunderstorms develop this
afternoon. As the cold front moves through this afternoon into
this evening, surface dewpoints will decrease significantly, and
overnight lows will be cooler than in recent nights. With that
said, lows will still be 7-10 degrees above normal. Cooling behind
the front, along with additional showers, will result in highs
Wed 5-10 degrees lower than today.

LONG TERM...Wednesday night through Monday...Models in good
agreement through Sunday but diverge Monday. Split upper trough
along the coast will move inland Wednesday night bringing showers
mainly to northern mountains and along the Nevada border.
Following short wave ridge will bring drying Thursday. Strong cold
front along the coast Thursday will weaken as it comes inland but
will still bring showers to all areas Friday and Friday evening.
Upper trough will move in from the Pacific Saturday with cool,
breezy, and showery weather for our area. Short wave ridge and
drying Sunday will be followed by another Pacific cold front and
more showers Monday, although model agreement is poor Monday.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Tuesday Tuesday Night Wednesday
Weather: Showers likely, then showers and possibly a thunderstorm after noon. High near 49. South wind 5 to 8 mph. Chance of precipitation is 90%. Showers and possibly a thunderstorm before midnight, then a chance of showers and thunderstorms after midnight. Low around 32. Southeast wind around 7 mph. Chance of precipitation is 100%. A chance of showers, with thunderstorms also possible after noon. Mostly cloudy, with a high near 44. South wind around 8 mph. Chance of precipitation is 30%.
Temperatures: 49 deg. F. 32 deg. F. 44 deg. F.
Wind direction: S SE S
Wind speed: 5-8 Around 7 Around 8
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Tuesday Tuesday Night Wednesday
Weather: Rain and snow showers. Some thunder is also possible. High near 41. South wind 13 to 16 mph. Chance of precipitation is 100%. Little or no snow accumulation expected. Snow showers. Some thunder is also possible. Low around 26. South wind around 15 mph. Chance of precipitation is 90%. Little or no snow accumulation expected. A 40 percent chance of snow showers. Some thunder is also possible. Mostly cloudy, with a high near 38. South wind 10 to 15 mph. New snow accumulation of less than a half inch possible.
Temperatures: 41 deg. F. 26 deg. F. 38 deg. F.
Wind direction: S S S
Wind speed: 13-16 Around 15 10-15
Expected snowfall: 0 in. 0 in. Trace 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.