THIS AVALANCHE FORECAST EXPIRED ON December 31, 2019 @ 6:58 am
Avalanche Forecast published on December 30, 2019 @ 6:58 am
Issued by Steve Reynaud - Tahoe National Forest

Blowing snow will continue today with increasing and shifting winds.  MODERATE avalanche danger will exist in near and above treeline areas due to wind slabs.  Below treeline areas will have low avalanche danger. 

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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SW winds increased yesterday and transported snow throughout the day onto NW-N-NE-E-SE aspects.  Light snow accumulations overnight added to the available snow for transport.  Winds shifted to the NE/E around 9pm last night and will continue to increase in speed through today with gale force ridge gusts.  These increasing NE/E winds will form fresh new wind slabs on SE-S-SW-W-NW-N aspects.  Wind slabs will be possible on all aspects in near and above treeline areas.   

Protected below treeline terrain will continue to have the best snow conditions and will also avoid the wind slab avalanche problem.  Wind scouring, blowing snow, and new cornice formation will all be occurring today in wind exposed areas.  Wind slabs that formed yesterday could get scoured today as new wind slabs form on other aspects.  Wind slabs could be hard or soft and be located near other areas that are scoured down to firm surfaces.    

recent observations
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Windy conditions with varying amounts of snow transport was reported throughout the forecast area yesterday.  A mix of small new wind slabs, old hard slabs, and wind scoured surfaces exist in near and above treeline areas.

Surface hoar was reported in a few locations.  Most reports had the surface hoar blown over or absent from the area.

Weather and CURRENT CONDITIONS
weather summary

A trace of new snow was reported throughout the forecast area overnight.  A cold NE/E flow will settle into our area for the next couple days.  NE wind gusts between 40 to 60mph will produce single digit to below zero wind chills for the mountains.  We get a brief break on Tuesday before another wave of precipitation passes through our area on Wednesday morning.  As of now, only minor amounts of new snow are forecasted with windy conditions.

CONDITIONS ALONG THE SIERRA CREST BETWEEN 8200 FT. AND 9200 FT. IN THE LAST 24 HOURS
Weather Station Map
Weather Station Table
6am temperature: 21 to 28 deg. F.
Max. temperature: 34 deg. F.
Average ridgetop wind direction: SW shifting to NE
Average ridgetop wind speed: 20 to 40 mph
Maximum ridgetop wind gust: 48 mph
New snowfall: Trace inches
Total snow depth: 44 to 50 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy. Chance of snow showers in the morning. Snow levels below 7000 feet. Chance of precipitation is 25%. Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 5%. Mostly cloudy then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 29 to 34. deg. F. 17 to 22. deg. F. 33 to 38. deg. F.
Mid Slope Winds: Northeast 15 to 20 mph with gusts to 45 mph. East 15 to 20 mph with gusts to 45 mph. East around 15 mph in the morning becoming light. Gusts up to 35 mph.
Expected snowfall: 20% probability up to 1 inch. 80% probability no accumulation. | SWE = less than 0.10 inch. No accumulation. | SWE = none. No accumulation. | SWE = none.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Cloudy. Chance of snow showers in the morning. Snow levels below 7000 feet. Chance of precipitation is 25%. Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 5%. Mostly cloudy then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 24 to 29. deg. F. 15 to 20. deg. F. 29 to 34. deg. F.
Ridge Top Winds: Northeast 20 to 35 mph with gusts to 60 mph. East 20 to 30 mph with gusts to 60 mph. East 15 to 25 mph. Gusts up to 45 mph decreasing to 35 mph in the afternoon.
Expected snowfall: 20% probability up to 1 inch. 80% probability no accumulation. | SWE = less than 0.10 inch. No accumulation. | SWE = none. No accumulation. | SWE = none.
Disclaimer

This avalanche forecast is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This forecast 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 forecast applies only to backcountry areas outside established ski area boundaries. This forecast describes general avalanche conditions and local variations always occur. This forecast expires 24 hours after the posted time unless otherwise noted. The information in this forecast is provided by the USDA Forest Service who is solely responsible for its content.

For a recorded version of the avalanche forecast call (530) 587-3558 x258