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.


This Avalanche Advisory was published on December 22, 2006:


December 22, 2006 at 1:00 am

Forecast Discussion:


This advisory was posted on Friday, December 22, 2006 at 7:35 am

Clear skies and high pressure are filling into the forecast area this morning. The storm system that impacted the forecast area yesterday and last night has exited to the east of the forecast area this morning. Westsouthwesterly ridgetop winds never reached forecast wind speeds last night. Winds have shifted to light to moderate northeasterly this morning.

Storm totals are running 7 to 19 inches across the forecast area with the greatest accumulations observed in the northern half of the forecast area. Storm total in the Mount Rose area is around 11 inches. New snow is measuring between 14 and 16% water content. The new snow has bonded well to old snow surfaces. Two easy to moderate shears within the lower portion of the new snow have been observed at several locations this morning along the Sierra Crest. Northeasterly winds this morning are starting to erode cornices on NE-E aspects. The peak of snowpack instability occurred last night during the height of the storm. A small possibility of natural avalanche activity exists today as air temperatures are expected to warm to near freezing at the 8,000' level. The vast majority of avalanche activity today will occur in response to human triggering on recently wind loaded N-NE-E aspects in near and above treeline areas.

For the Carson Pass area and northern half of the forecast area:

Near and above treeline, avalanche danger is CONSIDERABLE on recently wind loaded N-NE-E aspects, 33 degrees and steeper. Below treeline, avalanche danger is LOW with isolated pockets of MODERATE danger in open areas 35 degrees and steeper.

South of the Carson Pass area:

Near and above treeline, avalanche danger is MODERATE on recently wind loaded N-NE-E aspects 35 degrees and steeper. Below treeline, avalanche danger is LOW.

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 18 deg. F
Max. temperature at Sierra Crest past 24 hours: 31 deg. F
Average wind direction at Sierra Crest past 24 hours: westsouthwesterly
Average wind speed at Sierra Crest past 24 hours: 28 mph
Maximum wind gust at Sierra Crest past 24 hours: 54 mph
New snow fall at 8,200 feet past 24 hours: 7 - 19 inches
Total snow depth at 8,200 feet: 36 inches

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Mountain Weather Forecast For Today:
Partly cloudy skies
Temperature forecast for 8,000 to 9,000 feet: 25 - 31 deg. F
Ridgetop winds forecast for the Sierra Crest: northerly 30 - 40 mph, G 50 mph, by afternoon
Snowfall expected in the next 24 hours: 0 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
For today, partly cloudy skies with daytime highs 28 to 33 degrees F. Overnight lows 13 to 23 degrees F under partly cloudy skies. Saturday will be mostly cloudy with a slight chance of snow. Daytime highs around 38 degrees F.

Above 8000 Feet
For today, partly cloudy skies with daytime highs 25 to 31 degrees F. Winds out of the north at 30 to 40 mph with gusts to 50 mph. Overnight lows 17 to 25 degrees F. Northerly winds 40 to 50 mph with gusts to 65 mph. Saturday will be mostly cloudy with a slight chance of snow. Daytime highs around 35 degrees F. Westsouthwesterly ridgetop winds 30 to 40 mph with gusts to 60 mph are expected on Saturday.


The bottom line:


Andy Anderson - Avalanche Forecaster, Tahoe National Forest


Weather Observations from along the Sierra Crest between 8200 ft and 8800 ft:

0600 temperature: deg. F.
Max. temperature in the last 24 hours: deg. F.
Average wind direction during the last 24 hours:
Average wind speed during the last 24 hours: mph
Maximum wind gust in the last 24 hours: mph
New snowfall in the last 24 hours: O inches
Total snow depth: inches

Two-Day Mountain Weather Forecast - Produced in partnership with the Reno NWS

For 7000-8000 ft:

  Friday: Friday Night: Saturday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:

  Friday: Friday Night: Saturday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.