THIS AVALANCHE ADVISORY EXPIRED ON March 1, 2020 @ 7:11 am
Avalanche Advisory published on February 29, 2020 @ 7:11 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 avalanches are unlikely today but you may still encounter isolated areas where you could trigger a wind slab in high elevation, wind loaded terrain.  Cooler temperatures should diminish the roller ball and wet, loose activity but will likely result in widespread breakable crust today.  Pay attention to what Northerly winds are doing in areas where there is still soft snow.

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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  • Likelihood ?
    Certain
    Very Likely
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  • Size ?
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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 potentially problematic areas.    Northerly winds increased overnight with gusts in the mid 20's.  There isn't  much snow available for transport but be aware of the effect these winds are having on the snowpack in the northerly terrain.

Cornices are large right now.  Avoid traveling directly above or below large overhanging cornices, they may fail unpredictably or further back than you are expecting.

recent observations

Yesterday, small wet, loose sluffs were peeling off steeper, south facing terrain by 11 am. Finding good skiing and riding is still possible but conditions are challenging on many slopes.  Today will be a different  day with below freezing conditions,  cloudy skies and north winds starting to affect north facing slopes.  Don't expect sunny slopes to soften today and do expect some interesting and breakable crust on many aspects. 

 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 21 deg. F.
Max. temperature in the last 24 hours: 35 deg. F.
Average wind direction during the last 24 hours: ENE
Average wind speed during the last 24 hours: 7 mph
Maximum wind gust in the last 24 hours: 24 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: NA inches
weather

.SHORT TERM...Today through Monday night...An upper level system
and accompanying cold front will move through the area today,
bringing precipitation and gust winds to the region. The front is
expected to pass through Baker City and Burns around 6 am PST,
through Ontario and McCall around 9 am MST, Boise around 10 am
MST, Mountain Home around 11 am MST, and Twin Falls and Jerome
between noon and 1 pm MST. Northwest winds gusting to 25 mph will
follow the front, along with a period of snow showers above 3000
to 4000 ft and perhaps some brief sprinkles in the Snake River
Plain along the front. Precip will focus along the NV/ID border
tonight with up to 2 inches possible in southern Owyhee and Twin
Falls counties. Snow is again possible in southern Twin Falls and
far southeast Owyhee counties Sunday, but additional accumulations
will be an inch or less. It is worth mentioning that a convergence
zone may form in the western Magic Valley and far eastern Upper
Treasure Valley Sunday, spreading light snow farther north than
in our forecast. Confidence of this occurring is low at this time,
and therefore it is not in the official forecast. Winds will be
gusty again Sunday, especially south of Boise through Mountain
Home and into Owyhee County, where gusts could reach 40 mph.
Temps will be near normal today and a few degrees below normal
Sunday. Sunday night and Monday will be dry with temps again a
little below normal. Stronger northwest flow aloft will bring cool
and relatively moist air into the region late Monday night,
spreading light snow showers into the higher terrain of northern
Baker County and much of Valley County.

.LONG TERM...Tuesday through Saturday...Warmer. Northwest flow
aloft on Tuesday will shift into the west on Wednesday and the
southwest Thursday through Saturday as a high pressure ridge
amplifies to our east and a low pressure trough from the Gulf of
Alaska approaches the northwest coast. Temperatures will warm from
near normal on Tuesday to around 5 degrees above normal on
Wednesday and 5 to 10 degrees above normal Thursday and Friday.
Daytime temperatures on Saturday are expected to be slightly
cooler. Models differ on how they handle the trough to our west,
making precipitation chances uncertain near the end of the period.
Model blends currently show the best chances over northeast
Oregon and the central Idaho mountains Friday afternoon through
Saturday.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Saturday Saturday Night Sunday
Weather: Scattered snow showers. Mostly cloudy, with a high near 33. Calm wind becoming west around 6 mph in the afternoon. Chance of precipitation is 40%. Total daytime snow accumulation of less than a half inch possible. A 20 percent chance of snow showers before 11pm. Cloudy, then gradually becoming partly cloudy, with a low around 19. Light and variable wind. Sunny, with a high near 32. North wind 5 to 13 mph.
Temperatures: 33 deg. F. 19 deg. F. 32 deg. F.
Wind direction: W Light N
Wind speed: 6 Variable 5-13
Expected snowfall: Trace in. Trace in. 0 in.
Granite Mountain at 7700 feet.
  Saturday Saturday Night Sunday
Weather: Snow showers likely. Mostly cloudy, with a high near 23. West wind around 7 mph. Chance of precipitation is 60%. Total daytime snow accumulation of less than one inch possible. A 30 percent chance of snow showers, mainly before 11pm. Cloudy, then gradually becoming partly cloudy, with a low around 11. Wind chill values between -1 and 8. West wind 6 to 10 mph becoming north after midnight. New snow accumulation of around an inch possible. Mostly sunny, with a high near 21. Wind chill values between -2 and 7. North wind 11 to 14 mph.
Temperatures: 23 deg. F. 11 deg. F. 21 deg. F.
Wind direction: W W N
Wind speed: 7 6-10 11-14
Expected snowfall: Trace in. Trace 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.