THIS AVALANCHE ADVISORY EXPIRED ON February 29, 2020 @ 6:22 am
Avalanche Advisory published on February 28, 2020 @ 6:22 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The Avalanche Hazard today is Low today.  Remember though that LOW hazard does not mean NO hazard.  It means that sizeable avalanches are unlikely today but you may still encounter isolated areas where you could trigger a wind slab in high elevation, wind loaded terrain.  Today will be a warm day in the mountains and wet, loose avalanches will be possible as the snowpack warms on steep, sun affected terrain.

How to read the advisory


  • Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Wind Slab
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Small, wind slabs are still possible in high, alpine areas that were loaded by strong winds earlier this week. You may still be able to trigger these 6-12" thick slabs, especially in areas that had either a thin crust or a layer of faceted snow left over from last weeks high pressure conditions.  These wind slabs will likely not spread out or propagate much further than the area under your skis or snowmobile, but remember if you are in steeper or complex terrain, even a small avalanche can have big consequences. As you travel, look for slopes that don't have the obvious visual clues of wind affect, ripples across a slope or deeper deposits of snow drifted in under cornices or cliffs should be avoided or managed as problematic areas.  

Cornices are large right now and with warming temperatures are more likely to fail.  Avoid traveling directly above or below large overhanging cornices, they may fail unpredictably or further back than you are expecting.

Avalanche Problem 2: Loose Wet
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Expect to see roller ball and wet, loose activity increasing through the day today.  Very steep areas facing the sun may begin to shed snow as soon as the sun hits them beginning with E and SE aspects in late morning and following the sun around to the west throughout the day.  These kinds of avalanche problems are easy to anticipate and you generally have plenty of visual clues to let you know when the snowpack is loosing the battle against the sun.  Generally speaking you aren't likely to be skiing or riding these slopes right now as most of them have some variation of a breakable crust on them until they soften up later in the day.

recent observations

Yesterday, near Tamarack Resort, I found a pretty stable snowpack that was warming rapidly especially below 7000 feet.  The cold clear nights and warm days have been doing a good job building a fresh crop of near surface facets on slopes that are out of the direct sun and these may come back to haunt us when we see our next storm cycle.  Surprisingly though, yesterday on West Mountain, the breakable southern crust softened up enough to be creamy, soft and user friendly by early afternoon.  Mostly the snowpack is pretty straight forward right now.  If you see areas of wind affected snow, you may encounter wind slabs there, sunny slopes may produce small wet, loose slides as they warm, and overall the conditions are better than they should be given the temperatures this week. 

Our colleagues at the Sawtooth Avalanche Center have come up with a technical term that perfectly describes current conditions:  "WYSIWYG" for short, or phonetically, "whizzy-wig".  What does this mean to winter travelers???? WYSIWYG is what-you-see-is-what-you-get in terms of the snowpack.  While you need to be aware and adapt to changing conditions through the day, chances are the snowpack is not going to surprise you right now.  Any deep, lingering problems are either squashed or dormant and unlikely to produce avalanches unless conditions change drastically.

Despite the current "whizzy-wig" conditions, you still want to utilize safe travel protocols, keep your eyes on your partners as you travel and only expose one person at a time on  steep terrain.  Pay attention to changing conditions today and tomorrow as temperatures rise and stick to the cooler, shady slopes.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 28 deg. F.
Max. temperature in the last 24 hours: 35 deg. F.
Average wind direction during the last 24 hours: E
Average wind speed during the last 24 hours: 3 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

.SHORT TERM...Today through Sunday night...Southwest flow aloft
will increase today and bring high clouds in from the west, along
with warmer temperatures. An upper level storm will approach from
the west and northwest tomorrow, spreading showers into the
northern mountains. Snow levels will be around 4000 ft. in the
morning, and drop through the day and into tomorrow night.
Saturday will be 10-15 degrees cooler than today. Precip will
increase Saturday afternoon slowly decrease Saturday night into
Sunday as the upper low moves away to the south. Temperatures
Sunday will be similar to Saturday. Sunday night will be dry and
cool, with lows around 5 degrees below normal.

.LONG TERM...Monday through Friday...Northwest flow aloft on
Monday will shift into the west on Tuesday bringing warmer air and
an increasing chance of showers. The best chance of measurable
precipitation will be over the mountains of Baker County Oregon
and central Idaho, with snow levels 4000-5000 feet. A chance of
precipitation will continue over those areas through Wednesday. A
weak high pressure ridge will bring drier air Wednesday night and
Thursday. Precipitation chances will increase again on Friday, as
an upper level trough from the Gulf of Alaska approaches the
northwest coast, but model differences make timing uncertain.
Temperatures around 5 degrees below normal on Monday will warm to
a few degrees above normal on Tuesday and 5-10 degrees above
normal Thursday and Friday.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: Mostly sunny, with a high near 44. Calm wind becoming south around 6 mph in the afternoon. Isolated snow showers after 11pm. Snow level 5500 feet lowering to 5000 feet. Mostly cloudy, with a low around 30. South wind around 5 mph becoming calm in the evening. Chance of precipitation is 20%. Scattered snow showers. Mostly cloudy, with a high near 34. Calm wind becoming west around 6 mph in the afternoon. Chance of precipitation is 50%. New snow accumulation of less than a half inch possible.
Temperatures: 44 deg. F. 30 deg. F. 34 deg. F.
Wind direction: S S W
Wind speed: 6 5 6
Expected snowfall: 0 in. 0 in. Trace in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Mostly sunny, with a high near 35. South wind 7 to 10 mph. Scattered snow showers after 11pm. Mostly cloudy, with a low around 18. South wind around 11 mph. Chance of precipitation is 30%. New snow accumulation of less than a half inch possible. Snow showers likely. Mostly cloudy, with a high near 22. West wind 6 to 9 mph. Chance of precipitation is 70%. New snow accumulation of less than one inch possible.
Temperatures: 35 deg. F. 18 deg. F. 22 deg. F.
Wind direction: S S W
Wind speed: 7-10 11 6-9
Expected snowfall: 0 in. Trace in. Trace 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.