Avalanche Forecast published on December 18, 2018 @ 6:57 am
This Avalanche Forecast expires in 22 hours, 38 minutes
This Forecast is valid for 24 hours
Issued by Andy Anderson - Tahoe National Forest

MODERATE avalanche danger still exists in near and above treeline terrain, due to the possibility of lingering wind slabs. Human-triggered avalanches may remain possible today. Create a plan with safety margins to avoid the avalanche problems and maintain awareness of the conditions and terrain to stick to these safety margins while traveling in the backcountry.

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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Yesterday's storm did create some wind slabs on wind-loaded N-NE-E aspects and possibly some cross-loaded NW and SE aspects in near and above treeline terrain. Most of these wind slabs remain relatively small and do not extend very far away from the ridgelines. However, some uncertainty exists as to whether larger ones with enough snow to bury or injure a person could still be lurking in some of the most heavily wind-loaded areas. These wind slabs exist on top of a weak layer of old surface snow and human-triggered wind slab avalanches may remain possible today.

Avoiding wind-loaded areas where fragile wind slabs may exist represents a great safety margin for today. Planning to recreate in more sheltered terrain will also help take advantage of the soft unconsolidated snow. Maintain awareness of the conditions and terrain by looking for signs of wind-loading like cornices above a slope, blowing snow, or wind created textures on the snow surface.

Avalanche Problem 2: Loose Dry
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Some small, easy to manage, and mostly inconsequential loose dry sluffs could occur on steep slopes today as the new snow slides off of the old weak surface snow. However, some isolated sluffs could involve enough snow to interfere with a person's balance which could have consequences in more serious terrain.

recent observations

* Yesterday observations found small wind slabs along wind-loaded ridgelines on Castle Peak and on Silver Peak. In both areas, the wind slabs did not extend very far downslope. On Silver Peak ski kicks could trigger small wind slab failures. The largest of these measured about 1 ft deep at the top and extended about 10 to 20 ft from the ridgeline.

* In sheltered terrain yesterday, ski cuts could trigger small inconsequential loose dry sluffs on steep test slopes on Silver Peak.

* At lower elevations, observers found a thin rain crust at the base of the yesterday's new snow on Silver Peak and on Castle Peak. 

* Early season conditions still exist with lots of obstacles on or near the snow surface in many places.

Weather and CURRENT CONDITIONS
weather summary

After a final burst of snowfall yesterday morning, the storm departed the area leaving mostly clear skies for the rest of the day. A small high-pressure ridge has moved into the region and should keep the weather mostly clear for the next few days. Ridgetop winds have decreased and should continue to decrease over the next 36 hours, but some peak gusts could still climb into the 60 to 70 mph range today and tonight.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 23 to 30 deg. F.
Max. temperature in the last 24 hours: 25 to 32 deg. F.
Average wind direction during the last 24 hours: Southwest and South
Average wind speed during the last 24 hours: 30 to 35 mph
Maximum wind gust in the last 24 hours: 58 mph
New snowfall in the last 24 hours: 1 to 2 inches
Total snow depth: 28 to 32 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Today Tonight Wednesday
Weather: Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Partly cloudy then becoming clear. Snow levels 7500 feet. Chance of precipitation is 5%. Sunny. Snow levels 8000 feet. Chance of precipitation is 0%.
Temperatures: 43 to 49 deg. F. 27 to 33 deg. F. 45 to 50 deg. F.
Mid Slope Winds: Southwest 10 to 15 mph. Gusts up to 25 mph increasing to 35 mph in the afternoon. Light winds. Gusts up to 30 mph in the evening. Light winds.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. No accumulation. | SWE = none.
For 8000 ft. to 9000 ft.
Today Tonight Wednesday
Weather: Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Clear. Snow levels 7500 feet. Chance of precipitation is 5%. Sunny. Snow levels 8000 feet. Chance of precipitation is 0%.
Temperatures: 41 to 47 deg. F. 27 to 32 deg. F. 44 to 49 deg. F.
Ridge Top Winds: Southwest 15 to 30 mph with gusts to 70 mph. Southwest 20 to 30 mph with gusts to 60 mph. Southeast 15 to 25 mph. Gusts up to 45 mph decreasing to 30 mph in the afternoon.
Expected snowfall: No accumulation. | SWE = none. 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

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