THIS AVALANCHE FORECAST EXPIRED ON December 21, 2018 @ 6:50 am
Avalanche Forecast published on December 20, 2018 @ 6:50 am
Issued by Steve Reynaud - Tahoe National Forest

Moderate Avalanche Danger will continue today due to a wind slab avalanche problem as gale force winds with the possibility of light snow returns to our forecast area.  Wind slab avalanches will continue to be 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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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
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    Historic
    Very Large
    Large
    Small

Stubborn wind slabs that formed on Tuesday may be able to be triggered in isolated areas on N-NE-E aspects in near and above treeline terrain.  SW winds increased last evening to the strong to gale force range and are forecasted to continue today and into Friday.  While the amount of available snow for wind transport has declined, gale force winds today will move whatever snow is left and create a new round of wind slabs on NW-N-NE-E-SE aspects in near and above treeline terrain.  Light precipitation is possible this evening which will further add to the wind slab development.

Look for blowing snow and cornice formation-not all areas may have the same amount of wind transport occurring today.  Wind protected, below treeline terrain, continues to provide the best recreational opportunities away from the wind effected snow.

   

recent observations
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*  A difficult to trigger wind slab avalanche was intentionally triggered on a test slope near Ellis Peak (Blackwood Canyon area) yesterday.  This small avalanche was in near treeline terrain on a NE aspect.  It showed similar characteristics to recent wind slab avalanches from the last 2 days.

*  Signs of wind slab formation from Rubicon Peak (West Shore area) and Little Round Top (Carson Pass area) from yesterday. 

 

Weather and CURRENT CONDITIONS
weather summary

SW winds have been on the increase overnight and will continue into Friday as a fast moving system moves through our area.  Wind gusts of over 100mph are possible along the Sierra Crest today.  Light amounts of rain and high elevation snow is forecasted for this evening for the northern part of the forecast area along the Sierra Crest.  A break is expected Saturday with light winds before a potential larger storm is expected on Sunday into Monday.

CONDITIONS ALONG THE SIERRA CREST BETWEEN 8200 FT. AND 9200 FT. IN THE LAST 24 HOURS
Weather Station Map
Weather Station Table
6am temperature: 35 to 43 deg. F.
Max. temperature: 54 deg. F.
Average ridgetop wind direction: SW
Average ridgetop wind speed: 30 to 50 mph
Maximum ridgetop wind gust: 67 mph
New snowfall: 0 inches
Total snow depth: 25 to 30 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Thursday Thursday Night Friday
Weather: Partly cloudy. Snow levels 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Chance of snow showers after midnight. Snow levels 7000 feet decreasing to below 7000 feet after midnight. Chance of precipitation is 25%. Mostly cloudy. Chance of showers. Snow levels 7000 feet. Chance of precipitation is 25%.
Temperatures: 46 to 51. deg. F. 28 to 33. deg. F. 37 to 43. deg. F.
Mid Slope Winds: Southwest 15 to 20 mph. Gusts up to 35 mph increasing to 45 mph in the afternoon. Southwest 15 to 30 mph with gusts to 60 mph. Southwest 15 to 20 mph. Gusts up to 45 mph in the morning.
Expected snowfall: No accumulation. | SWE = none. 70% probability up to 1 inch. 30% probability of 1 to 3 inches. | SWE = less than 0.10 inch. Up to 1 inch. | SWE = less than 0.10 inch.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Partly cloudy. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 0%. Partly cloudy then becoming mostly cloudy. Slight chance of snow showers after midnight. Snow levels 7000 feet. Chance of precipitation is 25%. Mostly cloudy. Chance of snow showers. Snow levels 7000 feet. Chance of precipitation is 25%.
Temperatures: 43 to 48. deg. F. 25 to 30. deg. F. 33 to 39. deg. F.
Ridge Top Winds: Southwest 25 to 35 mph with gusts to 75 mph. Southwest 30 to 50 mph with gusts to 90 mph. Southwest 25 to 40 mph with gusts to 85 mph decreasing to 15 to 25 mph with gusts to 50 mph in the afternoon.
Expected snowfall: No accumulation. | SWE = none. 70% probability up to 1 inch. 30% probability of 1 to 3 inches. | SWE = less than 0.10 inch. Up to 1 inch. | SWE = less than 0.10 inch.
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