THIS AVALANCHE ADVISORY EXPIRED ON February 27, 2020 @ 6:58 am
Avalanche Advisory published on February 26, 2020 @ 6:58 am
Issued by George Halcom - Payette Avalanche Center
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The Avalanche Hazard today remains Moderate above 7,000 feet on wind loaded slopes steeper than 30 degrees.  Gusty winds have created wind slabs on multiple upper elevation slopes that are sensitive to the weight of a skier or snowmobiler.  Warmer temperatures and Sun will possibly cause small loose-wet avalanches on slopes getting direct Sun. 

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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Yesterday, we were able to get a small wind slab to fail under our skis. The cracking was limited to the area that I was effecting, which was small. The bonding was fairly poor and failed easily. As you get up higher, above 8,000 feet you are more likely to encounter small wind slabs 6-12 inches in depth. 

Winds picked up during the onset of Monday's teaser storm that put down a few inches near the Granite Mtn weather station. Above is a graph showing hours of gusts above 20 mph, and some hitting 36mph. Fresh, sensitive wind slabs from 6-12 inches in depth are possible in leeward terrain.

Some of the slabs may have formed on crusts that formed from the Sun. Expect poor bonding of the new snow, especially on slopes tipped towards the Sun. Local terrain is going to dictate loading and cross-loading patterns. Watch for changes in the density of the snow surface as you travel and obvious visual clues like ripples, drifts or partially covered old tracks to help identify potential wind slab or wind loaded slopes.  

Cornices are also getting large and are overhanging quite a bit in some areas.  Avoid traveling near the edges of corniced ridge lines.  Big cornices are unpredictable and can break further back than you expect.

 

 

 

 

 

Avalanche Problem 2: Loose Wet
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The temperature has been gradually rising, and along with it rising, the Sun has helped to break loose the powder we have been loving. We observed South slopes shedding snow in the form of point releases and loose-wet slides under strong Sun. More slides are possible as the Sun gets another day to work over the snow. The size and destructive power is likely going to be small, but worth keeping in mind, especially this afternoon. Stay out from under big slopes getting heated.

We noticed this solar induced wet slide on this South East slope yesterday afternoon.

advisory discussion

A HUGE thanks to the board and volunteers from the Friends of the Payette Avalanche Center for putting on another great fundraiser!  Thanks also to Jughandle Parade for the tunes as well!  That was probably the biggest fundraiser ever,  thanks also to everyone that came out and supported PAC and the FPAC!

recent observations

Yesterday, near Trail Lake, we observed some pretty good snow and a strong snow pack. Our pit and slope tests on a North slope above the lake was similar to what we have seen throughout the advisory area. The snow pack is right side up and failing in the upper 1-2 feet in compression but lacking the ability to propagate a fracture in extended column tests. We did get a small wind slab to fail in a small cross loaded WSW ridge.

small wind slab crown under the rocks

Most of the drifts and slabs that we noticed were small, and we did notice a crown from the winds of Monday under some rocks above Victor Lake. The Sun was strong at times when not filtered through clouds. We observed a small wet-loose slide on a SE slope during the afternoon, as well as a fresh thin crust that formed from the Sun.

 

 

 

 

 

 

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 20 deg. F.
Max. temperature in the last 24 hours: 25 deg. F.
Average wind direction during the last 24 hours: N
Average wind speed during the last 24 hours: 2 mph
Maximum wind gust in the last 24 hours: 11 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: NA inches
weather

 

Area Forecast Discussion
National Weather Service Boise ID
252 AM MST Wed Feb 26 2020

.SHORT TERM...Today through Friday night...Cold and Dry today with
scattered high clouds with passage of a weak shortwave. Upper
level ridge begins to build over the region Thursday and Friday
ahead of the next trough this weekend. Temperatures will gradually
warm each day reaching close to 60 degrees in the lower valleys by
Friday.

.LONG TERM...Saturday through Wednesday...An upper level storm will
move into the area Saturday, pushing a cold front through and
bringing precipitation. Snow levels will fall from a range of 4500
to 6500 feet in the morning to a range of 3500 to 6000 ft in the
late afternoon, leaving lower elevations with rain. Snow levels fall
farther overnight, but moisture will be limited by that time and
accumulating snow will still be limited to the mountains. By Sunday
night, the area will be dry, and a ridge will briefly move across
the region. Another storm will follow late Monday through Tuesday,
with colder air moving in on northwest flow aloft. Lower elevations
could see snow Tue morning, but it`s too early to have confidence at
this point. Moist cold northwest flow is forecast to continue into
Wed, with snow showers mainly in the mountains. Each of these
systems will be accompanied by gusty winds.

&&

.AVIATION...VFR. Increased mid-upper level cloud cover through late
afternoon. Surface winds, light and variable. Winds aloft to 10k
feet MSL, northwest 15-25kts.

 

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Wednesday Wednesday Night Thursday
Weather: Partly sunny, with a high near 36. Calm wind. Partly cloudy, with a low around 16. Calm wind. Sunny, with a high near 40. Calm wind.
Temperatures: 36 deg. F. 16 deg. F. 40 deg. F.
Wind direction: Calm Calm Calm
Wind speed: 0 0 0
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Wednesday Wednesday Night Thursday
Weather: A 20 percent chance of snow showers before 11am. Partly sunny, with a high near 27. South wind around 5 mph. Partly cloudy, with a low around 20. North wind around 5 mph becoming calm after midnight. Sunny, with a high near 31. Light west southwest wind.
Temperatures: 27 deg. F. 20 deg. F. 31 deg. F.
Wind direction: S N WSW
Wind speed: 5 5 Light
Expected snowfall: 0 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.