THIS AVALANCHE ADVISORY EXPIRED ON March 10, 2020 @ 7:27 am
Avalanche Advisory published on March 9, 2020 @ 7:27 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The Avalanche Hazard is Moderate today. The potential for wet, loose avalanches and wet sluffs will be the main concern this afternoon.  5-7 inches of new snow fell overnight. Wind slabs will be likely more sensitive where they are sitting on crusts and a variety of old snow surfaces. Human triggered loose dry sluffing is possible in steep terrain.

How to read the advisory


  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Loose Wet
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Wet, loose avalanches and wet sluffs have been the theme over the last 2 weeks as a spring weather pattern dominated the area.  Today the Sun will likely produce more slides, especially this afternoon as it dominates the sky and heats up the the new 5-7 inches of snow. 

 

 

Avalanche Problem 2: Loose Dry
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Its possible to ge some snow moving with you in steep terrain, especially on slopes that have a crust under the new snow. Loose dry sluffing yesterday was manageable, but given there to be around a foot of new snow over the last 24 hors, its possible to get knocked off your line in steep terrain. Sluff management is going to be necessary.

Avalanche Problem 3: Wind Slab
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Winds have started to calm down, and are forecasted to be fairly light over the next couple days. Yesterday we witnessed some wind activity that produced point releases, and we noticed some small slabs in a protected upper elevation area. The winds gusted upwards of 20MPH mostly before the storm.... Wind slabs are likely not bonded as well in areas that formed on crusts. It may be difficult to notice where the slabs lie as the new snow has come in under light winds and have likely camouflaged them well.

recent observations

Yesterday, up the Lick Creek drainage, East of McCall, we toured the Tsum drainage. We saw a lot of variation in snow from 5,400 feet at the bottom all the way up to 8,300 feet at the top. Below 6,800 feet the new 2-4 inches of snow hid the un frozen, rain saturated snow that still had not seen a freeze. Above 6,800 feet the snow pack did not have a crust on Northern aspects, but the interface was a bit denser from warmer temperatures creating a micro upside down layer that skied good and went un noticed. We were able to get some loose dry sluffing to run with us on our ski decent on a NW/N aspect. We witnessed a small natural (R1D1) wind triggered point release on a steep NW rocky slope during our morning climb in Tsum. Also, we observed many point releases on all aspects in the new snow. The Sun was limited to the morning, but did produce loose-wet slides around the rocks before getting shutdown by snow flurries in the afternoon. We did notice some small, shallow wind slabs on the upper ridges, and stout crusts beneath the new 6-8 inches the upper elevations that have seen Sun and colder temperatures.

 

South wet-loose from the Sun.

 

 

SSE wet loose slides from the fading Sun in the morning.

 

 

We were able to get this small rock to produce a mini slide in the new snow, Lower elevation, about 6,400' North.

 

 

A Roller ball that formed when I stopped on a lower elevation ENE slope.

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: 23 deg. F.
Average wind direction during the last 24 hours: NE
Average wind speed during the last 24 hours: 6 mph
Maximum wind gust in the last 24 hours: 20 mph
New snowfall in the last 24 hours: 6 inches
Total snow depth: NA inches
weather

Area Forecast Discussion
National Weather Service Boise ID
258 AM MDT Mon Mar 9 2020

.SHORT TERM...Today through Wednesday night...Showers will
continue today as a disturbance continues to impact the area. Snow
expected across the mountain locations, with rain or a rain-snow
mix possible across the valley locations. The heaviest snowfall is
expected to have fallen during the overnight hours, though light
snow accumulations remain possible through the evening hours.
Another 1 to 2 inches is possible across West Central and Boise
Mountains by midnight. Activity will weaken overnight with
building northwest flow. Generally dry conditions then expected
through Wednesday night. Temperatures will warm through the
period, with values reaching 5 to 10 degrees above normal by
Wednesday.

.LONG TERM...Thursday through Monday...An offshore ridge will allow
for mild and dry conditions ahead of the system moving across the
West Coast over the weekend. The trough is expected to move
southward along the California Coast, spreading showers across the
Intermountain West on Saturday. Wet conditions will continue through
the rest of the period, resulting in valley rain and mountain snow.
Temperatures ahead of the system will remain 6-8 degrees above
normal, while the trough will cool conditions back to the seasonal
average.

&&

.AVIATION...Mostly VFR with areas of MVFR to LIFR in precipitation.
Mountains obscured. Showers across SE OR and the West Central
Mountains spilling into the Treasure Valley this morning. Conditions
improving by 9/15z with another round of showers along the NV border
after 9/18z. Snow levels: 3000-4000 ft MSL. Surface winds: generally
variable 10 kts or less. Winds aloft near 10k ft MSL: W-SW 10-25
kts.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: A 50 percent chance of snow showers. Mostly cloudy, with a high near 38. Light west southwest wind. Total daytime snow accumulation of less than a half inch possible. Partly cloudy, with a low around 16. Calm wind. Sunny, with a high near 40. Light and variable wind.
Temperatures: 38 deg. F. 16 deg. F. 40 deg. F.
Wind direction: WSW Calm Light
Wind speed: Light 0 Variable
Expected snowfall: less than one half in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: Snow showers likely, mainly before noon. Mostly cloudy, with a high near 26. Calm wind becoming southwest around 5 mph in the afternoon. Chance of precipitation is 60%. Total daytime snow accumulation of around an inch possible. A 20 percent chance of snow showers before midnight. Partly cloudy, with a low around 15. West southwest wind around 5 mph becoming calm in the evening. Sunny, with a high near 28. South southwest wind 3 to 7 mph.
Temperatures: 26 deg. F. 15 deg. F. 28 deg. F.
Wind direction: SW WSW SSW
Wind speed: 5 5 3-7
Expected snowfall: 1 in. 0 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.