THIS AVALANCHE ADVISORY EXPIRED ON February 1, 2020 @ 6:57 am
Avalanche Advisory published on January 31, 2020 @ 6:57 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The avalanche hazard is Moderate today.  Natural avalanches were reported earlier this week as the snowpack adjusted to wind and storm loading.  Avalanches are possible today in the upper 1-2 feet of the snowpack. Weak layers can be found in the new snow.  Wind slabs are also a concern today in high Northerly terrain wind exposed terrain.  To minimize your risk, avoid areas with signs of obvious wind effect and stick to slopes less than 35 degrees today.

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Persistent Slab
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Local Snotel sites and ski resorts reported another 2+ feet of snow in the last 7 days. Temperatures fluctuated quite a bit during this time with the warmest days occurring Sunday and Monday.  The effect was predictable with avalanches on steep terrain occurring naturally in the new snow layers.  The last 2 days of warm temps and sun have allowed the snowpack to stabilize quickly.  There are still several layers of concern within the upper snowpack most notably being at least one layer of grauple mixed in to the new snow layers.  A layer of near surface facets also exists near the bottom of the new snow at the interface with the old snow surface.  These layers show the ability to propagate and could result in an avalanche 1-2 feet deep.  Play it safe today, avoid steep slopes and utilize good travel protocols while you enjoy the deep snow.

The photo below shows stability test results on the grauple layer that failed in an Extended Column Test ECTP 15 SC. 

Avalanche Problem 2: Wind Slab
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Expect to see sensitive wind slabs from a few inches to over a foot thick on a variety of upper elevation slopes.   Winds have been calm the last 2 days but winds earlier in the week were out of the NE, N and NW and moved a lot of snow.   Look for wind slabs near ridgetops, under corniced ridgelines and other wind exposed slopes.  In your face signs like cracking under your skis or snowmobile, a sudden change in how far your skis or sled are sinking in (ski/sled penetration) or obvious visual clues like rippled or sculpted snow  are all great indicators of wind slabs.  Avoid traveling in these areas and avoid growing cornices as well, some cornices are getting pretty large and can fail further back than you expect.

 

advisory discussion

*Snowmobiliers, the Granite Mountain closure went into effect on Janurary 15.  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 traffic.

recent observations

We traveled to the area near South Bruin Mountain and Fisher Creek Saddle yesterday and found plenty of deep snow in the middle elevations, evidence of mid storm avalanches that occurred earlier in the week with pretty impressive wind affect in the upper elevations.  Most impressive was the 9 1/2 foot deep snowpack that we found above 8000 feet. (see the 10 foot long probe picture below).  As noted above, the presence of 2 week layers in the upper snowpack produced test results in the Moderate range.  The amount of wind affect and wind slabs in the upper elevations combined with these weak layers should give you a good reason to play it relatively safe when choosing which slopes to ride or ski.  A 1-2 foot thick avalanche definitely has the ability to ruin your day.  While we are calling it Moderate Hazard today, I would put it into the category of a "Spicy" Moderate... human caused avalanches are possible on a variety of upper elevation slopes.

The last two days have also been incredibly warm and roller balls and small point releases were observed on steep terrain that was getting the full effect of the sun.  Warming snow is something to avoid on steeper terrain as well.  As slopes warm over the next few days, move to shadier, cooler slopes.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 22 deg. F.
Max. temperature in the last 24 hours: 30 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: 4 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

.SHORT TERM...Today through Monday...Ridging aloft today will
keep most of the area dry, but a few light showers are possible
across the north (mountains of Baker County and west central
Idaho). Temps will be 5-10 degrees above normal. So far this
morning, fog has been slow to develop mainly due to low clouds
(with an assist from some mid-level clouds). However, satellite
shows that significant breaks in the mid-level clouds are coming
in the next few hours, so will leave patchy fog in the forecast
around Ontario and Burns. Tonight will be dry as the upper flow
backs in advance of an approaching trough. Moisture from this
trough will spread into northeast Oregon late Saturday afternoon,
allowing for a slight chance of showers. The main push will come
Saturday night and Sunday. As southwest flow aloft increases
Saturday, temps will warm to 10-15 degrees above normal, with
highs in the 50s in most of the lower elevations, and possibly
reaching 60 near Rome, OR. As moisture increases Saturday night,
precip will spread from northwest to southeast across the CWA.
Snow levels will initially range from around 4500 ft in Baker
County to over 6500 ft in the south. As the system moves through,
snow levels will fall rapidly, reaching the ground at all
locations by Sunday afternoon. However, by this time most of the
precipitation will be over, and the Snake River Valley will most
likely only see a dusting. This system will bring a strong cold
front, and northwest winds will gust Sunday afternoon from 25 to
35 mph over much of the area. The strongest gusts are forecast for
the Upper Treasure Valley from south of Boise through Mountain
Home and into the far western part of the western Magic Valley.
Much colder air will bring temps down well below freezing Monday
morning, with readings in the teens and 20s in lower elevations
and single digits to teens in the mountains. Monday will be dry
with continued gusty northwest winds, and highs around 5 degrees
below normal.

.LONG TERM...Monday night through Friday...A brief period of dry,
breezy northerly flow is forecast Monday night and Tuesday.
Meanwhile, a surge of moisture will journey around an E Pacific
ridge, bringing widespread precipitation and breezy mountain winds
to our area starting Tuesday night. Snow levels will begin at
valley floors, but should gradually rise Wednesday night/Thursday
to around 4000-5000 feet MSL as warmer air nudges eastward. The
precipitation will also shift east over Baker County and the
central Idaho mountains, and temperatures will become milder for
Thursday. Thereafter, long-range models suggest the approach of a
cold low pressure system late this week. If this pattern holds
true, stronger winds with colder temperatures and showers can be
anticipated.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: A 40 percent chance of snow before 11am. Cloudy, with a high near 36. Light south wind. Total daytime snow accumulation of less than a half inch possible. Mostly cloudy, with a low around 30. Light south southeast wind. Partly sunny, with a high near 40. South wind 3 to 7 mph.
Temperatures: 36 deg. F. 30 deg. F. 40 deg. F.
Wind direction: S SSE S
Wind speed: Light Light 3-7
Expected snowfall: Trace in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: A 50 percent chance of snow before 11am. Cloudy, with a high near 29. South southwest wind around 9 mph. Total daytime snow accumulation of less than a half inch possible. Mostly cloudy, with a low around 26. South wind around 10 mph. Partly sunny, with a high near 32. South wind 11 to 15 mph.
Temperatures: 29 deg. F. 26 deg. F. 32 deg. F.
Wind direction: SSW S S
Wind speed: 9 10 11-15
Expected snowfall: Trace 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.