THIS AVALANCHE ADVISORY EXPIRED ON March 26, 2018 @ 6:38 am
Avalanche Advisory published on March 25, 2018 @ 6:38 am
Issued by Dave Bingaman - Payette Avalanche Center
bottom line

The avalanche hazard is LOW today.  2 days of cooling temperatures have made for a generally stable snowpack.  Small loose/wet avalanches are possible IF the sun makes an appearance over the next couple of days but these will be confined to steep, rocky areas that are getting direct sun affect.  Shallow wind slabs may still be found on northerly aspects.  Remember, LOW hazard does not mean no hazard, keep your eyes open for variable conditions.

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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Shallow wind slabs are still lingering close to the ridgelines.  Keep your eyes open for drifted, or pillowy looking deposits on E, NE, N or NW aspects if you are in steep, wind affected terrain.  Most of the drifts are very shallow and formed Friday night and Saturday morning.  Some of these shallow drifts may be camoflaging older, stiffer wind slabs below.  Hollow, or drummy feeling or sounding snow is a red flag for wind slab. 

Cornices have failed over the last few days as well and there are still some large cornices dotting the ridgelines.  Give overhanging cornices a wide berth right now as they will continue to fail as the snowpack warms up again early this week or if you get too close to the edge.

recent observations

The snowpack is doing a great job refreezing and healing itself right now.  The upper portion of the snowpack got saturated and 2 days of cooler weather have allowed the rain soaked portion of the snowpack to refreeze.  Some areas have a 2-3 inch crust that is sitting on less consolidated snow below but yesterday our pit tests showed little potential for triggering anything below the crust.  Skis are not penetrating this crust and snowmobiles are able to penetrate it in some areas but not in others.  If the sun or a combination of sun and warmer temperatures materialize tomorrow, expect the solar aspects to start shedding snow again in the form of small loose/wet avalanches.  So far over the last 2 days,  the high temps in the mountains did little to soften the crust even in the afternoon.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 14 deg. F.
Max. temperature in the last 24 hours: 21 deg. F.
Average wind direction during the last 24 hours: WSW
Average wind speed during the last 24 hours: 8 mph
Maximum wind gust in the last 24 hours: 32 mph
New snowfall in the last 24 hours: NA inches
Total snow depth: 63 inches
weather

SHORT TERM...Today through Monday...Showers associated with an
upper level trough have already moved north out of Nevada and are
affecting areas of the Snake Plain, Mountain Home towards the
Magic Valley at about 3 AM MDT. As the trough swings through the
Intermountain West today, moisture will wrap around the northern
portion of its associated surface low. At this time, models are
still in agreement that a band of moisture will develop, draping
across the Boise Mountains, through Canyon and Ada Counties and
west across the Owyhee Mountains. Snow levels will be near valley
floors and temperatures will be in the low 30s; this will be cold
enough for snow. Snow is expected to be light, generally less
that an inch, with higher amounts expected in the Boise Mountains,
across the Southern Highlands and the Owyhee Mountains, and in
southern Harney County. With a cold pool aloft and an unstable
environment associated with the upper level trough axis, a slight
chance for afternoon thunderstorms cannot be ruled out and remain
in the forecast. Temperatures will be about 10 degrees below
normal today, with a warming trend expected Monday in the trough`s
wake. As the upper level trough slides farther east tonight, a
moist northwest flow will anchor in for the near-term, for light
mountain showers.

.LONG TERM...Monday night through Saturday...Persistent northwest
flow will keep a chance of showers across the east- central
Oregon and west-central Idaho mountains though Thursday. An
embedded shortwave will extend the chance of showers into the
southern Idaho mountains on Wednesday. Showers return to the
mountains on Saturday as another weak wave moves into the Pacific
NW. The Snake Plain and southeast Oregon remain dry through the
period. Temperatures are within 5 degrees of normal with Friday
likely being the warmest day.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Sunday Sunday Night Monday
Weather: A 50 percent chance of snow showers. Some thunder is also possible. Mostly cloudy, with a high near 36. Calm wind becoming west northwest around 6 mph in the afternoon. Total daytime snow accumulation of less than a half inch possible. A 30 percent chance of snow showers before midnight. Mostly cloudy, with a low around 17. Northwest wind 5 to 8 mph becoming calm after midnight. New snow accumulation of less than a half inch possible. A 20 percent chance of snow showers after noon. Partly sunny, with a high near 36. Calm wind becoming west southwest 5 to 7 mph in the afternoon.
Temperatures: 36 deg. F. 17 deg. F. 36 deg. F.
Wind direction: NW NW WSW
Wind speed: 6 5-8 5-7
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Sunday Sunday Night Monday
Weather: Snow showers likely, mainly after noon. Some thunder is also possible. Mostly cloudy, with a high near 24. Light and variable wind becoming northwest 5 to 8 mph in the afternoon. Chance of precipitation is 70%. Total daytime snow accumulation of less than one inch possible. A 40 percent chance of snow showers, mainly before midnight. Mostly cloudy, with a low around 12. North northwest wind 6 to 11 mph. New snow accumulation of less than a half inch possible. A 30 percent chance of snow showers after noon. Partly sunny, with a high near 24. Northwest wind 5 to 8 mph. New snow accumulation of less than a half inch possible.
Temperatures: 24 deg. F. 12 deg. F. 24 deg. F.
Wind direction: NW NNW NW
Wind speed: 5-8 6-11 5-8
Expected snowfall: Trace 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.