Avalanche Forecast published on December 12, 2018 @ 6:48 am
This Avalanche Forecast expires in 11 hours, 54 minutes
This Forecast is valid for 24 hours
Issued by Steve Reynaud - Tahoe National Forest

Moderate Avalanche Danger is expected today throughout the forecast region due to a wind slab avalanche problem.  Increased winds overnight and through today will make wind slab avalanches possible in near and above treeline terrain.  Low avalanche danger will exist in below treeline 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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Strong to gale force SW winds overnight will make wind slab avalanches possible on NW-N-NE-E-SE aspects in near and above treeline terrain.  Throughout the day, winds will shift to the NW and then to the NE and remain strong in speed making wind slabs possible on all aspects in exposed near and above treeline terrain.  Some of these newly formed wind slabs could be deposited on top of surface hoar, making them easier to trigger.  Most of these wind slabs are expected to be small in size and not extend very far downslope.  These wind slabs could show soft or hard slab characteristics.  Many areas observed throughout the forecast region continue to have snow available for wind transport.

Look for blowing snow, cornice formation, wind pillows, and snow surface clues that wind transport has or is occurring.  Avoid steep wind loaded terrain. 

recent observations

*  Buried surface hoar has been found in the Carson Pass area, Desolation Wilderness area, Echo Summit area, Donner Summit area, Mt. Rose area, and the Independence Lake area.  The size, preservation, reactivity, and distribution of the surface hoar layer varies greatly by location.

*  Many areas still have soft snow available for wind transport in near and above treeline terrain.

*  On Sunday, a skier triggered a small slab avalanche that took him over a 200'+ cliff band on Mt. Tallac suffering serious injuries.

*  Mostly sufficient snow coverage exists along the Sierra Crest above 7000-7500'.  East of the Crest, snow coverage decreases with some areas still having adequate snow coverage for recreation.  Early season conditions exist in most areas.

Weather and CURRENT CONDITIONS
weather summary

Warming temperatures are expected over the next few days.  SW ridge winds were 60 to 80mph overnight with winds expected to shift to the NW then to the NE and remain strong in speed.  A weak system is expected to the north of our area on Friday that may bring small amounts of snow to the northern part of the forecast area.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 27 to 33 deg. F.
Max. temperature in the last 24 hours: 50 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 35 to 55 mph
Maximum wind gust in the last 24 hours: 65 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 27 to 32 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Today Tonight Thursday
Weather: Partly cloudy then becoming sunny. Partly cloudy Sunny
Temperatures: 39 to 44. deg. F. 19 to 27. deg. F. 40 to 45. deg. F.
Mid Slope Winds: West 10 to 15 mph with gusts to 40 mph in the morning becoming light. Light winds. Light winds.
Expected snowfall: None in. None in. None in.
For 8000 ft. to 9000 ft.
Today Tonight Thursday
Weather: Partly cloudy then becoming sunny. Clear then becoming partly cloudy. Sunny
Temperatures: 37 to 42. deg. F. 22 to 27. deg. F. 38 to 43. deg. F.
Ridge Top Winds: Northwest 25 to 35 mph with gusts to 80 mph becoming northeast 15 to 25 mph with gusts to 50 mph in the afternoon. Northeast 10 to 15 mph with gusts to 35 mph shifting to the southwest with gusts to 25 mph after midnight. Southwest 10 to 15 mph with gusts to 25 mph.
Expected snowfall: None in. None in. None 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

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