Avalanche Advisory published on March 31, 2018 @ 7:07:
This advisory is valid for 24 hours
Issued by Dave Bingaman -
bottom line

How to read the advisory

The Avalanche Hazard is generally Low today.  The potential for small loose/wet avalanches and failing cornices will increase as temperatures warm later in the day.  Steep, rocky slopes on the southern half of the compass will have the highest potential for wet slides.  Small, isolated wind slabs may also be found near ridgetops in east and north facing terrain.


Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Natural and human-triggered avalanches unlikely. Small avalanches in isolated areas or extreme terrain.
weather

HORT TERM...Today through Sunday...A weak disturbance will move
through the forecast area this morning, generating a few showers
along its route. Higher resolution models continue to indicate
shower development reaching from southern Baker County through the
Boise Mountains, with some variation as to how far north and
south the showers may reach. Adjusted shower coverage slightly to
shower a slightly higher confidence. Models then show this
activity moving south during the afternoon, potentially impacting
the Treasure Valley. Expect some gusty wind during this time as
well, with the Western Magic Valley again looking to be the most
favored location for wind. Temperatures will be slightly cooler
today in response to this system, but temperatures should still be
close to normal values. Dry northwest flow will return by late
tonight with dry conditions favorable through Sunday morning. An
approaching cold front will send some moisture across the West
Central Mountains, Boise Mountains, and into the higher elevations
of Baker County during the late afternoon hours. Expect a couple
degrees of warming on Sunday.

.LONG TERM...Sunday night through Friday...A strong cold front will
pass through southeastern Oregon on Sunday night and through
Southwestern Idaho on Monday morning. Strong northwest winds will
develop behind the front on Monday afternoon. Winds will be
strongest from Mountain Home through the Magic Valley, including the
Twin Falls and Jerome area. Scattered rain and snow showers will
accompany the frontal passage. Tuesday will be dry with light and
variable winds. A moist westerly flow aloft will bring unsettled
weather to the region Wednesday through Friday with periods of rain.
Snow levels will range from 6500 feet to 7500 feet, so only the
higher mountains will see snow during this time frame.

recent observations

Yesterday's cloud cover put a damper on the corn skiing.  We toured on sleds until 1 pm before finding soft snow.  East facing terrain had a supportable crust with about 1.5 inches of soft, melted butter on top.  Northerly terrain was variable but still had some soft, powderlike pockets.  Breakable crust was the name of the game through most of the day with an unsupportable surface on anything that was not tipped directly towards the sun.   The snow that is under the crust is cohesive and still resting on the old melt freeze layer around 50 cms down.  Despite the lack of snow available for transport, we observed minor wind loading near the ridgetops on East and Northeast terrain yesterday as winds ramped up to around 25 mph in the afternoon. 

Pay attention to changes on Sunday night as another storm enters our area bringing moderate snowfall amounts  and gusty winds to the upper elevations.  The new snow is going to have a difficult time bonding to the melt freeze surface that we have built up over the last week. 

In general, we are set up for a good spring season of skiing and riding as long as the lower elevation access sticks around.  Grooming will continue as conditions allow on the snowmobile routes and there is still plenty of snow in the upper elevations.

Avalanche Problem #1: Loose Wet

Loose, wet avalanches may occur as the sun and air temperature warm the upper snowpack today.  This type of avalanche is most likely on steep, upper or mid elevation rocky slopes that are getting direct sunlight in addition to above freezing mid day temperatures. Rollerballs, pinwheels and small point releases around rocks are all great indicators of warming snow.  If you notice any of these occurring, it is time to call it a day or move to a cooler, shadier aspect.  It didn't get warm enough for this to occur yesterday in the upper elevations but the lower and mid elevations were shedding snow in the late afternoon.

In addition to small loose/wet slides today, cornices are also a concern.  There are still plenty of large, overhanging cornices that are going to begin to fail as we see more warm weather through the rest of the spring.  Give overhanging cornices a wide berth especially later in the day as temps climb. Avoid travel on big cornices or directly below them.

In general, the snowpack right now is pretty stable.  Isolated areas of hazard may still be found and as you move into steeper terrain, keep in mind the consequences of the terrain if something did slide.  Small changes in the weather can have big effects on a spring snowpack so monitor conditions before you head out and pay attention to red flags and other warning signs while you are out.

advisory discussion

This will be our last advisory of the season unless we see a major change in conditions.  Thank you to all of our volunteer travel companions for joining us on good days and not so good days.  Also, a big thanks to Brian Peters for organizing the Friends fundraiser this year almost single handedly!  Thanks to all of the merchants and companies that donated to the fundraiser.  Finally, thank you to all of the folks that sent us observations or snow reports from across the advisory area throughout the winter.  If you would like to get involved with the Friends, please contact Susan Jenkins at the McCall Ranger District: 208-634-0400.

Tamarack Resort is hosting it's first ever Snowmobile Hillclimb competition which is being put on by RMSHA on April 7 and 8.  Don't miss out on a chance to get close to the action and see some great riders at a local venue.  Click here for more info.

CURRENT CONDITIONS  Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 27 deg. F.
Max. temperature in the last 24 hours: 35 deg. F.
Average wind direction during the last 24 hours: W
Average wind speed during the last 24 hours: 10 mph
Maximum wind gust in the last 24 hours: 22 mph
New snowfall in the last 24 hours: inches
Total snow depth: 60 inches
Two-Day Mountain Weather Forecast  Produced in partnership with the Reno NWS
For 7000-8000 ft.
  Saturday Saturday Night Sunday
Weather: A 20 percent chance of showers after noon. Mostly cloudy, with a high near 46. Calm wind becoming west 5 to 7 mph in the afternoon. A slight chance of rain showers before midnight, then a slight chance of rain and snow showers. Mostly cloudy, with a low around 25. West northwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 20% A chance of snow showers before noon, then a chance of rain showers. Mostly cloudy, with a high near 45. Light and variable wind becoming south southwest 5 to 8 mph in the morning. Chance of precipitation is 50%. New snow accumulation of less than a half inch possible.
Temperatures: 46 deg. F. 25 deg. F. 45 deg. F.
Wind direction: W WNW SSW
Wind speed: 5-7 5 5-8
Expected snowfall: 0 in. 0 in. Trace in.
For 8000-9000 ft.
  Saturday Saturday Night Sunday
Weather: A 20 percent chance of snow showers after noon. Mostly cloudy, with a high near 33. Calm wind becoming west 5 to 8 mph in the afternoon. A 20 percent chance of snow showers. Mostly cloudy, with a low around 23. West wind around 6 mph becoming light and variable. Snow showers likely, mainly after noon. Mostly cloudy, with a high near 32. South southwest wind 9 to 16 mph. Chance of precipitation is 60%. New snow accumulation of less than one inch possible.
Temperatures: 33 deg. F. 23 deg. F. 32 deg. F.
Wind direction: W W SSW
Wind speed: 5-8 6 9-16
Expected snowfall: 0 in. 0 in. 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.