THIS AVALANCHE ADVISORY EXPIRED ON December 5, 2017 @ 6:45 am
Avalanche Advisory published on December 4, 2017 @ 6:45 am
Issued by Steve Reynaud - Tahoe National Forest

Moderate avalanche danger will exist with human triggered avalanches possible.  Wind slabs will continue to be a problem in near treeline and above treeline terrain due to recent and continuing strong to gale force winds.  Identify where wind slabs exist and avoid steep wind loaded terrain. 

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
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    Historic
    Very Large
    Large
    Small

Wind slabs could continue to exist on NW-N-NE-E-SE aspects in near treeline and above treeline terrain from the SW storm winds yesterday.  Winds shifted to the NE yesterday afternoon/evening and increased in speed overnight.  New wind slabs will be possible on SE-S-SW-W-NW aspects in near treeline and above treeline terrain.  These new wind slabs will continue to build today and into Tuesday as strong to gale force NE/E winds continue. 

Look for areas of blowing snow, cornice formation, and snow surface clues as to where wind slabs have been forming.  Avoid steep wind loaded terrain where wind slabs exist.

recent observations

-Evidence of reactive wind slabs on Donner Summit

-4 to 6'' of storm snow from Hwy. 50 north on Sunday.

 

 

Weather and CURRENT CONDITIONS
weather summary

A strong ridge of high pressure will continue to build across the Western US through this week with mostly clear skies and no storms in sight.  Strong to gale force NE/E winds will continue into Tuesday. Valley inversions will intensify through the week with cold overnight temperatures in low lying areas.  A gradual warming trend will begin and continue into next weekend. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 10 to 16 deg. F.
Max. temperature in the last 24 hours: 29 deg. F.
Average wind direction during the last 24 hours: SW shifting to NE
Average wind speed during the last 24 hours: 35 to 45 mph
Maximum wind gust in the last 24 hours: 83 mph
New snowfall in the last 24 hours: Trace to 1 inches
Total snow depth: 16 to 34 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Sunny Clear Sunny
Temperatures: 25 to 30 deg. F. 14 to 19 deg. F. 34 to 39 deg. F.
Wind Direction: NE E E
Wind Speed: 10 to 15mph. Gusts up to 35mph increasing to 50mph in the afternoon. 10 to 15mph with gusts to 50mph. 10 to 15mph. Gusts to 45mph decreasing to 35mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Sunny Clear Sunny
Temperatures: 22 to 27 deg. F. 15 to 20 deg. F. 33 to 38 deg. F.
Wind Direction: NE NE E
Wind Speed: 20 to 30mph. Gusts to 40mph increasing to 60mph in the afternoon. 30 to 45mph. Gusts to 80mph increasing to 90mph after midnight. 20 to 35mph with gusts to 70mph decreasing to 15 to 25mph with gusts to 60mph.
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

This avalanche advisory is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This advisory covers the Central Sierra Nevada Mountains between Yuba Pass on the north and Ebbetts Pass on the south. Click here for a map of the forecast area. 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 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

For a recorded version of the Avalanche Advisory call (530) 587-3558 x258