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 advisory was posted on Thursday, February 8th, 2007 at 6:58 am

The bottom line: Near and above treeline, avalanche danger is MODERATE on wind loaded N-NE-E aspects 35 degrees and steeper. Below treeline, avalanche danger is MODERATE above 7,000' where the potential for sluff activity exists on previously snow covered slopes 35 degrees and steeper.

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A series of weather systems are still on track to impact the forecast area over the next several days. A break in snowfall will occur today before another, stronger system moves over the forecast area late this afternoon and overnight. Ridgetop wind speeds are expected to decrease today after maximum gusts of 89 mph were observed last night. Air temperatures are expected to warm this morning before decreasing during the afternoon hours. Snow level is not expected to rise above 6,500' today, despite rising freezing levels this morning. The storm system expected to arrive overnight tonight is forecast to deposit 8-12 inches of new snow along the Sierra Crest by late Friday morning.

Storm totals are running 5-7 inches across the forecast area this morning. This new snow has been deposited on high density wind slab and/or melt-freeze crust in avalanche start zones. Ridgetop winds averaging near 40 mph and gusting to near 90 mph caused wind loading and increased new snow deposition on N-NE-E aspects in near and above treeline areas. There is a significant density difference and some traditionally poorly bonding new snow grain types at the old/storm snow interface. This has created a good bed surface for avalanche activity. Human triggered slab avalanches less than 1 foot deep, occurring at the interface of the old and new snow, are possible today. Human triggered sluff avalanche activity is possible today below treeline on slopes 35 degrees and steeper. Sluffs are anticipated mainly in areas above 7,000' where new snow sits on top of a hard melt-freeze crust. Additional snowfall expected overnight is not anticipated to create instability deeper within the existing snowpack at this time.

The bottom line: Near and above treeline, avalanche danger is MODERATE on wind loaded N-NE-E aspects 35 degrees and steeper. Below treeline, avalanche danger in MODERATE above 7,000' where the potential for sluff activity exists on previously snow covered slopes 35 degrees and steeper.

With the return of precipitation to the forecast area, we will resume posting advisories each morning, prior to 7am.

Brandon Schwartz, Avalanche Forecaster

Today's Central Sierra Weather Observations:

0600 temperature at Sierra Crest (8,700 feet): 27 deg. F
Max. temperature at Sierra Crest past 24 hours: 29 deg. F
Average wind direction at Sierra Crest past 24 hours: southwesterly
Average wind speed at Sierra Crest past 24 hours: 38 mph
Maximum wind gust at Sierra Crest past 24 hours: 79 mph
New snow fall at 8,200 feet past 24 hours: 5-7 inches
Total snow depth at 8,200 feet: 36 inches

Mountain Weather Forecast For Today:

Cloudy skies with snow showers, increasing in the afternoon.
Temperature forecast for 8,000 to 9,000 feet: 29 - 34 deg. F
Ridgetop winds forecast for the Sierra Crest: Westsouthwesterly 25 - 35 mph, gusting to 60 mph
Snowfall expected in the next 24 hours: 8 - 12 inches, mainly overnight

2 Day Mountain Weather Forecast:

7000 to 8000 Feet
Today, cloudy skies with scattered snow showers, increasing in the late afternoon. Snow level 6,500'. Snow accumulation 1 inch. Southwest winds at 15 to 30 mph, gusting to 45 mph. Daytime highs 38 to 42 degrees F. Tonight, cloudy skies with snow. Snow accumulation 3 to 5 inches. Lows 27 to 32 degrees F. Southwest winds at 20 to 35 mph. Friday, cloudy skies with snow, decreasing in the afternoon. Snow accumulation 4 to 6 inches. Daytime highs 36 to 40 degrees F. Winds are forecasted to be out of the southwest at 20 to 30 mph, gusting to 40 mph.

Above 8000 Feet
Today, cloudy skies with scattered snow showers, increasing in the late afternoon. Snow accumulation 1 to 2 inches. Westsouthwest winds at 25 to 35 mph, gusting to 60 mph. Daytime highs 32 to 37 degrees F. Tonight, cloudy skies with snow. Snow accumulation 4 to 6 inches. Lows 23 to 28 degrees F. Southwest winds at 30 to 40 mph, gusting to 65 mph. Friday, cloudy skies with snow, decreasing in the afternoon. Snow accumulation 4 to 6 inches. Daytime highs 28 to 34 degrees F. Winds are forecasted to be out of the southwest at 25 to 35 mph, gusting to 50 mph.

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:
	Thursday:	Thursday Night:	Friday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Thursday:	Thursday Night:	Friday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.