THIS AVALANCHE ADVISORY EXPIRED ON March 24, 2020 @ 7:08 am
Avalanche Advisory published on March 23, 2020 @ 7:08 am
Issued by George Halcom - Payette Avalanche Center
bottom line

The Avalanche Hazard is Low today.  You may be able to trigger isolated wind slabs in upper elevation Northerly terrain. Winds will gust today out of the South upwards of 20 mph. Remember, LOW hazard does not mean NO hazard. 

How to read the advisory


  • Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Wind Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
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    Small

Today, Wind slabs may not be of much an issue until later in the day when we start getting snow with the forecasted winds gusting into the 20's out of the South. Hopefully the winds calm down before the snow falls. Not much snow exists for transport right now, but there is still soft snow in shady places.

Expect growing slabs, 2-8 inches thick, in the upper elevations, that are likely going to form on a crust, and in some places the wind will scour all the new snow easily off of firm Sun and temperature crusts

Remember! if you are skiing shady, northerly terrain you increase your risk of finding scattered old wind slabs.  Even small avalanches can have big consequences if you are in committing terrain. 

 

advisory discussion

If you are coming to visit the McCall, Donnelly or Cascade areas over the next few days, please be aware that we are a small, rural area with limited EMS, Medical and other resources available.  Many bars and restaurants are closed or open only for take out orders.  Both Ski Resorts are closed. We are taking the Corona Virus threat very seriously and if you are a visitor, we need you to take the precautions described by the CDC to help keep our communities safe.  You can find more info about open businesses and other community information at: https://valley-county-covid-19-response-valleycounty.hub.arcgis.com/

Also,  Please don’t ride your Snowmobile at Brundage Mountain Resort, or within the BMR permit area which includes areas adjacent to the resort. It is illegal even though the resort is closed. Also, with the lifts closed many skiers are utilizing the resort for backcountry skiing. There are PLENTY of other areas to snowmobile nearby. Please reference the USFS Payette National Forest Winter Travel Map for more info.

https://www.fs.usda.gov/I…/FSE_DOCUMENTS/stelprdb5446292.pdf

recent observations

Yesterday, on Granite mountain, the bright Sun softened the snow  enough to allow for good ski purchase in the afternoon. We observed small loose-wet point releases and roller balls near the rocks under full Sun. The snow softened beyond its prime around 1:30 on a due South aspect. 

CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.:
0600 temperature: 28 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: E
Average wind speed during the last 24 hours: 5 mph
Maximum wind gust in the last 24 hours: 20 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: NA inches
weather

Area Forecast Discussion
National Weather Service Boise ID
313 AM MDT Mon Mar 23 2020

.SHORT TERM...Today through Wednesday night...
A large upper level trough is tracking southward along the Pacific
Northwest coast this morning, bringing an increase in clouds and
winds to the region. By this afternoon, this low will encourage
moist, dynamic flow aloft for OR and ID, supporting showers and
thunderstorms during this afternoon and evening. Low- to mid-
level winds will be as high as 35-45 mph, which will likely mix
down to the surface with showers and instability present.
Sustained surface winds will also be enhanced outside of showers,
with up to 20-30 mph sustained winds over southeast Oregon and far
southwest Idaho. A cold frontal passage is forecast to move from
NW to SE later this evening, lowering snow levels to near valley
floors as shower activity decreases. However, isolated to
scattered showers will still continue for both Tuesday and
Wednesday with a rain/snow mix possible for lower elevations.
Mountain elevations above 4000 feet MSL can expect to see periods
of light to moderate snow accumulations through Wednesday.
Temperatures will lower 10 degrees or more from Monday to Tuesday
behind the cold front passage, with additional cooling into
Wednesday that will feel more like late February.

.LONG TERM...Thursday through Monday...The upper level trough
will move off to the southeast Thursday, and a fast-moving ridge
will pass through Thu night, bringing dry weather. Moist northwest
flow aloft will return Friday, bringing showers to the region,
especially the higher terrain of the north. This will continue
through Saturday. An upper level trough is forecast to move in
Saturday night along with moist west flow in its wake, bringing
additional showers Saturday through Monday. Temperatures will be
below normal through Saturday, then rise to above normal Sunday
and Monday. Although based on ensembles, this forecast tracks much
closer to the 00Z run of the operational ECMWF than the GFS,
in which the latter is much drier for the weekend.

&&

.AVIATION...Initially VFR with increasing clouds from the
northwest through the day. Then, areas of MVFR/IFR and mountain
obscurations in showers and thunderstorms this afternoon/evening
as a cold front moves through from the northwest from 18Z to 06Z
tonight. Snow levels: around 5kft, becoming 3500ft by Tue
morning. Surface winds less than 10 kt through 18Z, becoming
southwest to northwest 10-20 kt with higher gusts after 18Z. Wind
gusts 30 to 40 kt late this afternoon in southeast Oregon, with
gusts 20 to 30 kt elsewhere. Winds aloft at 10kft MSL: SW 20-40 kt
by 09z/Mon.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Monday Monday Night Tuesday
Weather: A slight chance of snow showers before noon, then rain showers likely. Some thunder is also possible. Mostly cloudy, with a high near 42. East southeast wind 6 to 9 mph becoming south in the afternoon. Winds could gust as high as 21 mph. Chance of precipitation is 70%. Little or no snow accumulation expected. Rain showers before midnight, then a chance of snow showers. Some thunder is also possible. Low around 25. South wind 5 to 8 mph becoming calm after midnight. Chance of precipitation is 80%. New snow accumulation of less than a half inch possible. Snow showers likely, mainly after noon. Mostly cloudy, with a high near 36. Calm wind becoming south southwest 5 to 7 mph in the afternoon. Chance of precipitation is 70%. New snow accumulation of around an inch possible.
Temperatures: 42 deg. F. 25 deg. F. 36 deg. F.
Wind direction: ESE becoming South S becoming Calm Calm becoming SSW
Wind speed: 6-9 Gusting to 21 mph 5-8 5-7
Expected snowfall: 0 in. less than one half in. 1 in.
Granite Mountain at 7700 feet.
  Monday Monday Night Tuesday
Weather: Snow showers, mainly after noon. Some thunder is also possible. High near 31. South wind 11 to 14 mph, with gusts as high as 23 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 1 to 2 inches possible. Snow showers. Some thunder is also possible. Low around 18. South southwest wind 6 to 11 mph becoming west northwest after midnight. Chance of precipitation is 90%. New snow accumulation of 3 to 5 inches possible. Snow showers. High near 24. Southwest wind 7 to 9 mph. Chance of precipitation is 90%. New snow accumulation of 1 to 3 inches possible.
Temperatures: 31 deg. F. 18 deg. F. 24 deg. F.
Wind direction: S SSW becoming WNW SW
Wind speed: 11-14 Gusting to 23 mph 6-11 7-9
Expected snowfall: 1-2 in. 3-5 in. 1-3 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.