THIS AVALANCHE ADVISORY EXPIRED ON February 5, 2019 @ 6:33 am
Avalanche Advisory published on February 4, 2019 @ 6:33 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The Avalanche Hazard is High.  Natural Avalanches are Likely, and Human triggered avalanches are very likely. With over a foot of new snow in the last 24 hours and gusty winds around 22 MPH out of the South West have created wind slabs that are not bonding to the older snow.  Be smart, use safe travel protocols avoid steep terrain, and be aware of changes in the snow pack throughout the day on different aspects.  

How to read the advisory


  • Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Avalanche Problem 1: Wind Slab
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    Certain
    Very Likely
    Likely
    Possible
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  • Size ?
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With over a foot of new snow in the last 24 hours and gusty winds around 22 MPH out of the South West have created wind slabs that are not bonding to the older snow. Yesterday there was a Natural Wind slab avalanche observed just North of Brundage, on Clough Point, and a Snowmobile triggered slab on the Fisher Creek road bank. Wind Loaded, steep avalanche terrain should be avoided today.

Pay attention to wind stiffened snow near the ridge tops today, or places that show obvious wind effect in the form of ripples or small pillows. 

Do not let your guard down, be smart, use safe travel protocols including 1 at a time on steep terrain and be aware of changes in the snow pack throughout the day on different aspects.

 

Avalanche Problem 2: Storm Slab
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    Certain
    Very Likely
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Over a foot of new snow in the last 24 hours has fallen, and is tending to be a bit thicker/slabby, especially near the old snow interface where it has not bonded very well. Storm slabs will likely be found in protected areas today. 

Do not let your guard down, be smart, use safe travel protocols including 1 at a time on steep terrain and be aware of changes in the snow pack throughout the day on different aspects.

advisory discussion

PAC will issue 3 Advisories per week through the remainder of the winter as long as funding is available.

Please be aware that there are areas that are CLOSED to motorized traffic in the McCall  and greater West Mountains area.  Just because there are tracks in some areas, does not mean they are open.  Please respect all users and closures.  See the Payette Winter Travel Maps for clarification.  Both the East and West maps can be downloaded on the Avenza app on your phone or are available at trailheads and local shops.   IT IS YOUR RESPONSIBILITY TO KNOW WHERE YOU ARE AND WHERE THESE CLOSURES EXIST.  

recent observations

Yesterday, we toured North of Brundage Mtn. Visibility was challenging with strong winds and snow. We observed the new snow not bonding well, and failing easily in our test pits, mit pits, sled cuts, and we talked to a snowmobiler that set of a shallow slab near the road bank on the Fisher Cr Road. Also, Clough Point, Just North of Brundage ski area, slid naturally yesterday afternoon about 6 inches deep, 75 feet wide, and nearly choked off the groomed trail.

Here is a video of one of our Test pits Yesterday on Granite Mtn.

 

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: 23 deg. F.
Average wind direction during the last 24 hours: S
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: 8 inches
Total snow depth: 63 inches
weather

Area Forecast Discussion
National Weather Service Boise ID
347 AM MST Mon Feb 4 2019

.SHORT TERM...Today through Wednesday...An upper low digging along
the coast will keep moist southwest flow over the area today.
Focus of precipitation will be in the mountains while development
in lower valleys is less widespread. Have extended the Winter
Weather Advisory in the west-central Idaho mountains until 10AM
this morning with an additional 1 to 3 inches expected. Today
will also be breezy across far southeast Oregon and through the
lower Snake Plain in response to passage of a surface low. Though
confidence is low, could see a lightning strike or two over
southeast Oregon and southwest Idaho south of the Snake Plain this
afternoon as convective indicies are marginal. The upper low
along the coast will move into the interior NW overnight, shifting
precipitation development into central Idaho. This will include
the upper Treasure Valley and western Magic Valley where light
snow accumulation is possible Tuesday morning. Tuesday is cooler
with snow showers continuing in the mountains while valleys trend
drier. The upper low pulls into eastern Idaho Wednesday drawing in
much colder air behind it. Temperatures will run about 10 degrees
below normal on Wednesday while gusty northwest winds add a
noticeable windchill.

.LONG TERM...Wednesday night through Sunday...Unsettled and
unseasonably cool weather will continue. As the upper level trough
exits to the east Wednesday night, southeast Oregon and southwest
Idaho will be under northerly flow aloft. With modified arctic air
and clearing skies, overnight lows will be in the teens and
single digits in the valleys and below zero in the mountains.
Temperatures on Thursday will remain below freezing, except in the
Treasure Valley, where afternoon highs in the mid 30s are
expected. Temperatures will moderate slightly Thursday night and
Friday under southwest flow aloft ahead of the next upper level
trough as it drops south from British Columbia. The trough will
bring scattered snow showers, mainly Friday through Saturday, but
there will be a chance of snow showers through Monday.
Temperatures will average 5 to 10 degrees below normal.

&&

.AVIATION...Widespread mountain obscuration and MVFR/IFR
conditions in snow above 4500 feet MSL. Scattered showers of rain
or mixed rain and snow in the valleys with periods of MVFR/IFR
conditions. Surface winds east to south 10-20 kts with gusts to 30
kts, decreasing to 10 kts or less this evening. Winds aloft at
10k feet MSL southwest 30- 40 kts.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: Snow showers. High near 34. South southeast wind 7 to 9 mph, with gusts as high as 20 mph. Chance of precipitation is 80%. New snow accumulation of 1 to 2 inches possible. Snow showers likely, mainly before 11pm. Cloudy, with a low around 21. South southeast wind 5 to 7 mph becoming calm in the evening. Chance of precipitation is 60%. New snow accumulation of less than one inch possible. Snow showers likely, mainly after 11am. Cloudy, with a high near 26. Calm wind becoming west around 6 mph in the afternoon. Chance of precipitation is 60%. New snow accumulation of less than one inch possible.
Temperatures: 34 deg. F. 21 deg. F. 26 deg. F.
Wind direction: SSE SSE W
Wind speed: 7-9 5-7 becoming calm 6
Expected snowfall: 1-2 in. Less than one in. Less than one in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: Snow showers. High near 23. South southeast wind 11 to 17 mph, with gusts as high as 26 mph. Chance of precipitation is 90%. New snow accumulation of 2 to 4 inches possible. Snow showers. Low around 15. South wind 7 to 14 mph, with gusts as high as 23 mph. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible. Snow showers, mainly after 11am. High near 18. South southwest wind 5 to 7 mph becoming west in the afternoon. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.
Temperatures: 23 deg. F. 15 deg. F. 18 deg. F.
Wind direction: SSE S SSW becoming West
Wind speed: 11-17, Gusts to 26 7-14, Gusts to 23 5-7
Expected snowfall: 2-4 in. 1-3 in. 1-3 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.