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 December 11, 2007 9:43 AM
Click here for a detailed map of the SAC forecast area

No danger rating issued, limited data.
Today's Advisory:
At this time, we are still working with limited data. However, natural and human triggered avalanche activity in not expected today. Collision with shallow buried objects such as rocks, down trees, and stumps remains the major threat to backcountry travelers.

The forecast area has remained under cold northeasterly flow since late Friday afternoon. Moderate to strong ridgetop winds have impacted the forecast area for the past several days. This pattern is expected to continue through today. A very weak weather system, will move into the forecast area overnight, causing a brief period of westerly flow to develop. A few light snow showers may occur with this system, but significant snowfall is not expected. A shift to light northeasterly flow is anticipated for Wednesday afternoon.
A shallow snowpack ranging from 15 to 20 inches deep exists throughout the forecast area. Remote sensors along the Sierra Crest have shown around 5 inches of settlement has occurred since the end of the past storm on Friday. Snow pit data taken from a variety of protected and wind loaded areas on Tamarack Peak (Mount Rose area), a few miles north of Castle Peak (Sierra Crest area), and a few hundred feet north of the summit of Carson Pass (Sierra Crest area) have all show higher density snow near the ground, with increasingly lower density snow near the surface. The most abrupt density change has been observed around 30 cm (1 foot) above ground level in all of these snow pits. No significant shears have been observed within the snowpack at this time. Beginning late Friday afternoon, moderate to strong northeast winds began scouring snow from traditional avalanche start zones on N-NE-E aspects in near and above treeline areas. Some of the avalanche start zones have been scoured all the way back to bare ground, reducing the likelihood of avalanche activity on N-NE-E aspects. Sufficient anchoring of a shallow snowpack has kept instability from forming near and above treeline on more the recently wind loaded S-SW-W aspects. Some very light upslope snowfall occurred overnight in the extreme southern portion of the forecast area. Remote sensors report 1 to 2 inches of new snow in the Sonora Pass area.

The bottom line: At this time, we are still working with limited data. However, natural and human triggered avalanche activity in not expected today. Collision with shallow buried objects such as rocks, down trees, and stumps remains the major threat to backcountry travelers.

With so many shallow buried objects, the best option for backcountry travel is touring on snow covered Forest Service Roads.

The next update to this advisory will occur when conditions warrant.
Brandon Schwartz, Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 7 deg. F
Max. temperature at Sierra Crest past 24 hours: 21 deg. F
Average wind direction at Sierra Crest past 24 hours: Northeast
Average wind speed at Sierra Crest past 24 hours: 55 mph
Maximum wind gust at Sierra Crest past 24 hours: 114 mph
New snow fall at 8,200 feet past 24 hours: 0 to 2 inches
Total snow depth at 8,200 feet: 15 inches
Mountain Weather Forecast For Today:
Partly cloudy to clear skies.
Temperature forecast for 8,000 to 9,000 feet: 22 to 28 deg. F.
Ridgetop winds forecast for the Sierra Crest: Northeast at 35 to 45 mph with gusts to 70 mph, decreasing in the afternoon.
Snowfall expected in the next 24 hours: 0 to trace inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Today, partly cloudy in the morning, then clearing. Daytime highs 23 to 29 deg. F. East winds at 15 to 25 mph with gusts to 40 mph.

Tonight, partly cloudy skies with overnight lows 18 to 24 deg. F. Light winds expected.

For Wednesday, mostly cloudy skies with daytime highs around 32 deg. F. Light winds expected.

Above 8000 Feet:
Today, partly cloudy in the morning, then clearing. Daytime highs 22 to 28 deg. F. Northeast winds at 35 to 40 mph with gusts to 70 mph. Winds shifting to east at 20 to 30 mph with gusts to 50 mph in the afternoon.

Tonight, partly cloudy skies with overnight lows around 23 deg. F. Northeast winds at 10 to 15 mph, shifting to west after midnight.

For Wednesday, mostly cloudy skies with daytime highs around 31 deg. F. West winds at 10 to 15 mph, shifting to north in the afternoon.

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