Avalanche Advisory published on March 17, 2017 @ 5:47 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The Avalanche Danger is MODERATE  today at all elevations/aspects due to the possibility of loose, wet avalanches resulting from warm temperatures and recent rainfall that has saturated the upper snow pack.  Cornice failures are also a concern,  the overhanging snow has become unstable as a result of the warm, wet weather this week.  The snow surface will be refrozen this morning but will be thawing through the day and is unlikely to refreeze until Sunday evening.

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

Most of the wet-loose natural avalanche activity has already taken place this week during another round of high elevation rain and above average temperatures.  Local Snotel Sites have lost between 20 and 30 inches of their snow pack in the last 7 days as a result of the wet, warm weather.  Yesterday and last night provided a much needed cooldown with temperatures dropping into the mid 20's.  The snow surface will start out firm today and gradually soften again as temperatures climb this afternoon.  Temperatures are forecasted to remain above freezing through Sunday night even in the mid and upper elevations.  With the lack of freezing temperatures, especially below 7,600 feet, you still run a good chance of starting a loose wet avalanche in steep terrain.  Scattered rain showers tonight and rain tomorrow will increase the potential for natural and human caused wet slides through the next 48 hours.

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

Many of the ridgelines in the area are still sporting some very large, overhanging cornices.  We had a report of a large, human triggered cornice failure earlier this week and also have seen many areas where large sections of cornice have already succumbed to the pull of gravity.  Cornice failures are very common in the spring and we have a bumper crop of monster cornices this year.  Avoid travel on or near large cornices and stay off slopes that have large, overhanging cornices above them.

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 yesterday.  You can still see the evidence of last week's natural avalanche cycle with some decent sized crowns dotting the steeper slopes throughout the mountains.  You can also see plenty of wet slide debris on steep terrain as well, some of it was pretty significant.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 26 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: WSW
Average wind speed during the last 24 hours: 8 mph
Maximum wind gust in the last 24 hours: 26 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches

SHORT TERM...Today through Saturday...Southwest flow aloft will
continue through the short term, and embedded within that flow a
weak short wave trough will move through the area Saturday
afternoon. The flow is moist, and showers will move into southeast
Oregon and the West-Central Mountains generally west of McCall
this afternoon. Overnight, the precipitation spreads south and
east, and the chance for precip covers the entire area. Saturday,
as the short wave trough moves through, an accompanying cold front
will move through as well. Instability will increase ahead of and
along the front, and there is a slight chance of thunderstorms
generally south and east of a line from Rome, Oregon to Caldwell
to Warm Lake Saturday afternoon. Precipitation totals through the
short term will average 1/3 to 3/4 of an inch in the mountains,
with a tenth or less in the lower elevations. This rainfall will
exacerbate flooding on some rivers. See the hydrology section
below for more. Temperatures will remain quite mild today, but
turn cooler tomorrow. Overnight lows tonight will be very mild
(around 15 degrees above normal) due to cloud cover and wind.

.LONG TERM...Saturday night through Friday...An active pattern
still looks likely for the long term as a series of troughs will
move into the PACNW. The first upper level trough is expected to
move east of the area on Saturday night into Sunday morning, but
leave a stationary boundary placed across the middle of the CWA
for Sunday. Precip is expected along this boundary and models
suggest it will weaken later on Sunday, then be pushed north by
surface southwest flow ahead of the next upper trough. Showers
continue through the period with trough passage and a cold front
early Wednesday morning and possibly another on Thursday.
Temperatures are expected to remain above normal through at least
Wednesday, and likewise, snow levels will stay 6000 ft and higher.
Thursday and Friday look to be cooler and more near normal.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Isolated showers after noon. Partly sunny, with a high near 50. East southeast wind 5 to 9 mph. Chance of precipitation is 20%. Rain likely, mainly after midnight. Cloudy, with a low around 38. Southeast wind around 7 mph. Chance of precipitation is 70%. Showers. High near 47. South southeast wind 8 to 11 mph. Chance of precipitation is 90%.
Temperatures: 50 deg. F. 38 deg. F. 47 deg. F.
Wind direction: ESE SE SSE
Wind speed: 5-9 Around 7 8-11
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Isolated snow showers after noon. Mostly cloudy, with a high near 37. South wind 11 to 18 mph, with gusts as high as 28 mph. Chance of precipitation is 20%. A chance of rain and snow before midnight, then rain. Low around 36. Breezy, with a south wind 18 to 20 mph, with gusts as high as 29 mph. Chance of precipitation is 100%. Little or no snow accumulation expected. Rain showers before noon, then rain and snow showers. High near 38. Breezy, with a south wind 18 to 23 mph, with gusts as high as 33 mph. Chance of precipitation is 100%. Little or no snow accumulation expected.
Temperatures: 37 deg. F. 36 deg. F. 38 deg. F.
Wind direction: S S S
Wind speed: 11-18, Gusts to 28 18-20, gusts to 29 18-23, gusts to 33
Expected snowfall: Trace in. Trace 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.