THIS AVALANCHE ADVISORY EXPIRED ON March 25, 2017 @ 6:59 am
Avalanche Advisory published on March 24, 2017 @ 6:59 am
Issued by Kent May - Payette Avalanche Center
bottom line

The avalanche danger today will start out LOW. However, later this afternoon and into tonight, moderate to strong winds and new snow are in the forecast and the danger will rise to MODERATE due to human triggered wind and storm slabs being possible. As snow and wind continue over the weekend, make note of where the wind is blowing the new snow and pick terrain accordingly.

How to read the advisory

Avalanche Problem 1: Wind Slab
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With the incoming storm, south winds are forecasted in the 20 and 30 mph range. These winds combined with new snow will do good job of building new wind slabs on north facing and cross loaded terrain. Today and over the weekend, watch what the wind is doing. What direction is it coming from? Is it loading up high on the slopes, or is it blowing so hard that the snow is loading further down the slope or not loading at all?

Avalanche Problem 2: Loose Dry
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Forecasts are calling for 2-10 inches today and an additional 3-8 tonight depending on where you are in the PAC advisory area. This new snow will be falling on a multitude of different existing snow surfaces. The number one suspect surface to watch for over the weekend will be melt freeze crust. The new snow on crust will have a heck of a time bonding and will be ripe and ready to get pushed around. If only a few inches of snow falls, the problem will be merely dry loose sluffs, however, tonight and into tomorrow as the snow piles up storm slabs will take the place of what was small manageable sluffs.

advisory discussion

***This is the last daily avalanche advisory for the season.

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recent observations

No new natural or human triggered avalanches have been reported over the last 24 hours.

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 27 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: 7 mph
Maximum wind gust in the last 24 hours: 25 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: NA inches
weather

Today snow, mainly after noon. High near 27. Breezy, with a south wind 23 to 28 mph, with gusts as high as 37 mph. Chance of precipitation is 100%. Total daytime snow accumulation of 3 to 7 inches possible.

Tonight snow before midnight, then snow showers after midnight. Low around 22. Breezy, with a south wind 17 to 22 mph decreasing to 6 to 11 mph after midnight. Chance of precipitation is 100%. New snow accumulation of 4 to 8 inches possible.

SHORT TERM...Today through Saturday...Southwest flow aloft ahead
of an impressive upper level trough is visible off the Pacific NW
coast this morning. Precipitation associated with this frontal
system will spread across southeast Oregon this morning, and into
southwest Idaho by this afternoon. Strong southwest flow should
keep the Snake Plain dry south and east of Boise through late this
afternoon, before filling in across the Snake Plain and spreading
into the Magic Valley this evening. Temperatures will be a tricky
forecast today, with lower 60s expected in the Magic Valley, and
much cooler temperatures across the north and west in the rain
cooled air. Significant precipitation is expected across the
central Idaho mountains this afternoon and evening, with snow
levels around 5500-6500 feet, with light accumulations in the
mountain valleys. The higher peaks above 7500 feet will see
significant snow accumulations of 6-10 inches with this system.
Precipitation is expected to taper off in SE Oregon late tonight
and southwest Idaho early Saturday morning. With cooler air aloft
on Saturday, scattered showers are expected to develop across the
entire region on Saturday afternoon with daytime heating creating
instability.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Friday Friday Night Saturday
Weather: A chance of snow before noon, then rain and snow. High near 38. Northeast wind 5 to 8 mph becoming south in the afternoon. Chance of precipitation is 100%. Total daytime snow accumulation of less than a half inch possible. Rain and snow before midnight, then rain and snow showers likely. Low around 28. South southeast wind around 5 mph becoming calm after midnight. Chance of precipitation is 100%. Little or no snow accumulation expected. Rain and snow showers likely, mainly after noon. Mostly cloudy, with a high near 40. Light and variable wind. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.
Temperatures: high 38 deg. F. low 28 deg. F. high 40 deg. F.
Wind direction: northeast southeast variable
Wind speed: 5-8 5 light
Expected snowfall: less than .5 in. 0 in. Less than .5 in.
Granite Mountain at 7700 feet.
  Friday Friday Night Saturday
Weather: Snow, mainly after noon. High near 27. Breezy, with a south wind 23 to 28 mph, with gusts as high as 37 mph. Chance of precipitation is 100%. Total daytime snow accumulation of 3 to 7 inches possible. Snow before midnight, then snow showers after midnight. Low around 22. Breezy, with a south wind 17 to 22 mph decreasing to 6 to 11 mph after midnight. Chance of precipitation is 100%. New snow accumulation of 4 to 8 inches possible. Snow showers likely. Mostly cloudy, with a steady temperature around 22. Southwest wind around 9 mph. Chance of precipitation is 60%. New snow accumulation of 1 to 2 inches possible.
Temperatures: high 27 deg. F. low 22 deg. F. high 22 deg. F.
Wind direction: south south southwest
Wind speed: 23-28 gusting 37 17-22 decreasing to 6-11 9
Expected snowfall: 3-7 in. 4-8 in. 1-2 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.