THIS AVALANCHE ADVISORY EXPIRED ON February 6, 2020 @ 7:25 am
Avalanche Advisory published on February 5, 2020 @ 7:25 am
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard is Moderate today.  Human triggered storm slab avalanches are going to be possible today with more new warmer snow . Human triggered wind slab avalanches are still possible but decreasing. Wind sheltered areas are suspect for harboring Storm slabs, and buried surface hoar.

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Storm Slab
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Temperatures have risen overnight and a good amount of new snow is forecasted through the next few days. Most of the older snow surface got impacted by the wind, temperature, and Sun, which are going to have different bonding with new snow. In protected areas, there is  fluffy low density, cold dry snow that won't do a great job of supporting a heavier load.

As the day, and the storm progresses, storm slabs will build up and become more sensitive. Steep slopes, especially in areas that are sheltered are going to be likely suspects. Use safe travel protocols in steep terrain, spread out, and travel one at a time.

Avalanche Problem 2: Wind Slab
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The wind has been notably cold, and respectfully strong over the last few days, and has produced small natural avalanches. Some of the wind slabs developed on firm surfaces that are a challenge to stick to with some small facets. Yesterday, I was able to kick loose a small piece of wind slab with my ski. Cracks did not propigate. Many of the wind slabs that have observed are very strong, and have done a good job of bonding. 

Avalanche Problem 3: Persistent Slab
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Buried surface hoar, and near surface facets are is still visibile in our stability pits, and giving us moderate results, however it has not been able to propigate with the unconsolodated loose, dry snow above it.The wind has done a good job of breaking down the surface hoar. Most of the crystals are prettty small and fragmented under a lens.

Sensitivity to triggereing may increase as we put heavier, warmer snowloads on top. Sheltered, corners in terrain, are likely suspspects along with building storm slabs. 

 

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 traffic.

recent observations

Yesterday, we toured out East of McCall to Buckhorn Mountain, Maloney Lake area. The upper elevation East slopes got pounded by the wind and created some neat features, but variable skiing and snowmobiling. We were able to find some good snow on Western slopes that were softer and more protected, which is where we also found some surface hoar buried beneath the newer snow about a foot down. We could get the layer of surface hoar to fail moderately in compression, but it lacked propagation due to the soft unconsolidated snow above it. Under the lens the fragments were small and broken from wind.

 

Along our ski tour, we were able to only get a small piece of wind slab to break off. We ski cut some steep wind slabs and did not even see a crack. Most of the upper elevation wind effected snow is very stout. 

 small 1-3 inch wind slab on a firm South aspect that broke easily on some near surface facets

 Skiing an upper elevation ENE wind effected slope into Maloney Lake.

 

 

Western slopes with softer snow were producing not only good skiing and snowmobiling, but also small loose point releases under the full sun yesterday.

 The buried surface hoar layer that did not propagate (ECTN, CTM)...WNW slope at 8,200 feet above Maloney Lake.

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 9 deg. F.
Max. temperature in the last 24 hours: 11 deg. F.
Average wind direction during the last 24 hours: NE
Average wind speed during the last 24 hours: 5 mph
Maximum wind gust in the last 24 hours: 14 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: NA inches
weather

 

 

Area Forecast Discussion
National Weather Service Boise ID
351 AM MST Wed Feb 5 2020

.SHORT TERM...Today through Saturday...Light snow has developed
early this morning ahead of a warm front moving into the region.
Steady precipitation will continue through the day across much of
the region. Mountains will remain snow all day while lower valleys
will see a changeover to rain by this evening as snow levels
gradually rise with the warm front and precipitation intensity
decreases. The Baker valley and Weiser basin could see freezing
rain this afternoon, though confidence is low and expect any
occurrence to be brief. Forecast snow totals through Thursday,
still highlight Baker county, the upper Weiser Basin and w-central
Idaho mountains. In the Snake Plain areas to the northeast of a
line from Weiser to Caldwell to Kuna will see the most snow with
1 to 2 inches expected mostly through early this afternoon. Lower
elevations of southeast Oregon and the western Magic valley will
see lesser amounts (both liquid and snow) with this event. Snow
levels rise tonight and precipitation will taper off for much of
the region as the warm front lifts northeastward. Many locations
will see little drop in temperatures from this afternoon highs.
Upslope northwest flow will keep light snowfall across the
e-central Oregon and w-central Idaho and Boise mountains into
Friday with snow levels rising above 5kft. Lower elevations will
see dry and mild conditions Thursday and Friday. Models in good
agreement on a shortwave trough and accompanying cold front
dropping into the Pacific NW on Saturday with another round of
rain/snow along with gusty winds.

.LONG TERM...Saturday night through Tuesday...Lingering snow
showers and cold temperatures can be expected through Sunday as
northeast flow aloft develops in the wake of a trough. A brief
respite from precipitation is expected Monday before the next low
pressure system approaches Tuesday. Long range models still have
timing and intensity discrepancies, but currently agree that an
arctic air mass will drop southward into the northern U.S.
sometime on Tuesday. If this holds true, this will support strong
winds ahead and along the cold front Tuesday, and much colder
temperatures over the area for Wednesday and Thursday. Currently,
the ECMWF keeps the coldest temperatures east of our area, while
the GFS/Canadian models bring much of the arctic air directly over
the Pacific Northwest. Stay tuned for updates.

&&

.AVIATION...Mountains obscured. Snow coverage increasing, becoming
widespread by 05/14Z. MVFR/IFR with local LIFR due to snow and
ceilings until snow levels rise. Snow levels: At valley floors,
rising from west to east...to 4kft MSL for w-central ID, and 5kft+
for rest of area by tonight. Surface winds: westerly 10 kt or
less, except 12-25 kt for KBNO/KJER/KTWF. Winds aloft at 10kft
MSL: NW 40- 55 kt.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow. High near 26. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 100%. New snow accumulation of 3 to 7 inches possible. Snow. Low around 26. Light west southwest wind. Chance of precipitation is 100%. New snow accumulation of 2 to 4 inches possible. Snow before 11am, then rain and snow. High near 36. West southwest wind around 6 mph. Chance of precipitation is 100%. New snow accumulation of 1 to 2 inches possible.
Temperatures: 26 deg. F. 26 deg. F. 36 deg. F.
Wind direction: S SW WSW
Wind speed: 5 Light 6
Expected snowfall: 3-7 in. 2-4 in. 1-2 in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: Snow. High near 21. South southwest wind 6 to 8 mph. Chance of precipitation is 100%. New snow accumulation of 6 to 10 inches possible. Snow. Temperature rising to around 28 by 4am. Southwest wind 6 to 11 mph becoming west northwest in the evening. Chance of precipitation is 100%. New snow accumulation of 3 to 7 inches possible. Snow. High near 29. West wind 10 to 13 mph. Chance of precipitation is 100%. New snow accumulation of 2 to 4 inches possible.
Temperatures: 21 deg. F. 28 deg. F. 29 deg. F.
Wind direction: SSW SW-NW W
Wind speed: 6-8 6-11 10-13
Expected snowfall: 6-10 in. 3-7 in. 2-4 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.