THIS AVALANCHE ADVISORY EXPIRED ON January 13, 2017 @ 8:06 am
Avalanche Advisory published on January 12, 2017 @ 8:06 am
Issued by George Halcom - Payette Avalanche Center
bottom line

Today, the avalanche danger is CONSIDERABLE for elevations above 6,000 feet. Human triggered avalanches are LIKELY on steep, wind drifted slopes, and rocky slopes, especially those facing the north half of the compass. Southern aspects will likely produce loose wet slides as the Sun warms up the snow today.

Below 6,000 feet MODERATE avalanche danger exists and human triggered slides are possible.

How to read the advisory


  • Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Wind slabs have been lingering...this past Saturday, skiers were kicking them off, and yesterday, we were able to kick a cornice and get some wind slab to pull out on a a North aspect leading into Hum Lake (see photo below)...we also noticed fresh natural wind slab crowns beneth the steep rocks above Hum Lake from the new snow about 10-12 inches deep. South-soutwest winds continued to load up Northern aspects...Be on the lookout for Windslbs and tender cornices On NW through East Aspects.

Avalanche Problem 2: Loose Wet
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With all of the snow, and not much sun until today, we will likely see the snowpack adjust to solar radiation as the surface warms up, and loose, wet avalanche danger increases, especially on steep, rocky Southern aspects.

advisory discussion

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recent observations

Yesterday, we were able to kick a cornice and get some wind slab to pull out on a a North aspect leading into Hum Lake (see photo below)...we also noticed fresh natural wind slab crowns beneth the steep rocks above Hum Lake from the new snow about 10-12 inches deep.

We also noticed a temperature/rain crust buried about a foot down at the new snow interface, and got some hard CT25 results.

 

weather

.SHORT TERM...Colder drier air has come in behind yesterday`s cold front but southward-moving upper low in Oregon will still support isolated snow showers in sern Oregon and swrn Idaho today. Latest satellite and radar imagery shows a few echoes in southern Malheur County. Northern areas have become quite cold with mostly clear skies, light winds, and deep snow cover. Through Friday the Oregon upper low will move south along 120W reaching southern California late Friday. Dry northwesterly flow aloft will come into our CWA. Temps will continue to lower, although patchy fog and stratus will limit radiational cooling at night. NAM has stratus throughout the Snake Basin Friday morning but is an outlier. Consensus suggests at least some fog/stratus, however. Light winds through Friday. .LONG TERM...Friday night through Thursday...An upper ridge and surface high pressure will remain over the area through early next week, resulting in below normal temperatures and the potential for valley fog and stratus. Another moist Pacific Storm will reach the the northwest coast late on Tuesday for widespread precipitation through Thursday. There are some differences in the onset of this event but all model projections show significant precipitation across the forecast area mid week. Mountains will see snow but the valleys look to see mostly rain with temperatures around normal by Wednesday.

Two-Day Mountain Weather Forecast Produced in partnership with the NOAA-NWS
McCall Airport at 5021 feet.
  Thursday Thursday Night Friday
Weather: Patchy fog before 11am. Otherwise, mostly cloudy, then gradually becoming sunny, with a high near 23. Wind chill values between zero and 10. Calm wind becoming south southwest around 5 mph in the afternoon. Areas of dense fog after 11pm. Otherwise, mostly clear, with a low around -6. Wind chill values between -11 and -16. Light and variable wind. Areas of dense fog before 11am. Otherwise, sunny, with a high near 20. Wind chill values between -6 and -16. Light and variable wind.
Temperatures: 23 deg. F. -6 deg. F. High 20 deg. F.
Wind direction: South-southwest Variable Variablet
Wind speed: 5 Light Light
Expected snowfall: 0 in. 0 in. 0 in.
Granite Mountain at 7700 feet.
  Thursday Thursday Night Friday
Weather: Mostly cloudy, then gradually becoming sunny, with a high near 17. Wind chill values between -4 and 6. Southwest wind 5 to 9 mph. Mostly clear, with a low around 8. Wind chill values between -3 and 2. Southwest wind 3 to 7 mph Sunny, with a high near 22. Wind chill values between -2 and 8. Southwest wind around 6 mph.
Temperatures: 17 deg. F. Low 8 deg. F. 22 deg. F.
Wind direction: Southwest Southwest Southwest
Wind speed: 5 to 9 3 to 7 6
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

This avalanche advisory is provided through a partnership between the Payette National Forest and the Friends of 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.