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 Tuesday, February 20th, 2007 at 6:46 am

The bottom line: Avalanche danger is LOW for all elevations and aspects.

Cloud cover is expected to slowly increase today as the next storm system approaches the forecast area. Ridgetop winds shifted to westerly overnight. Wind speeds are expected to increase this afternoon. Maximum daytime air temperatures were around 10 degrees cooler yesterday than observed last weekend. Daytime air temperatures are expected to warm 2-3 degrees F. over yesterday. A slight chance to a chance of precipitation enters the forecast tonight and tomorrow. At this time, the main energy of the approaching storm system is expected to hold off until Thursday.

Snow surface conditions throughout the forecast area consist of melt-freeze crust on all aspects below 8,500'. The exception exists in the Carson Pass and Luther Pass areas, where unconsolidated snow surface conditions remain after Sunday's snowfall. Above 8,500, a mix of melt-freeze crust, rough wind scoured and smooth wind scoured snow surfaces exist. Many of these area are covered with a very thin layer of graupel or surface hoar crystals. These hard snow surfaces and potential weak and poorly bonded surface grains raise a possibility of poor bonding of any new snow that falls on the existing snow surface. Get out and observed you favorite locations so that you have some idea of what to expect with the approaching storm system.

An overall stable snowpack exists throughout the forecast area at this time. Layer bonding tests performed over the past few days indicate good strength within the existing snowpack structure. The current snowpack is in good condition to handle new snow loading. Future instability concerns at this time are mainly focused on bonding to the existing snow surface and failure within the storm snow. Think good thoughts and be nice to your neighbor, the approaching storm system has the potential for snow level to drop all the way down to 1,000'-2,000' with plenty of remaining energy after cold front passage occurs.

The bottom line: Avalanche danger is LOW for all elevations and aspects.

At this time, we are still short $8,000 in funding for our operating budget this winter. If you use this service with any regularity and would like to continue to do so, please show your financial support for the Sierra Avalanche Center. You may make a tax deductible donation directly to us via Paypal or by sending a check to our address listed above, c/o the Truckee Ranger Station. A financial graph showing the amount of fundraising completed this season and our overall budget is available by clicking here. The financial support already received this winter from a variety of users is greatly appreciated.

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 24 deg. F
Max. temperature at Sierra Crest past 24 hours: 33 deg. F
Average wind direction at Sierra Crest past 24 hours: easterly, shifting to westerly
Average wind speed at Sierra Crest past 24 hours: 30 mph
Maximum wind gust at Sierra Crest past 24 hours: 59 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 51 inches

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Mountain Weather Forecast For Today:
Becoming partly cloudy in the afternoon.
Temperature forecast for 8,000 to 9,000 feet: 33 - 38 deg. F.
Ridgetop winds forecast for the Sierra Crest: westerly 20 - 30 mph, G 50 mph, increasing to 30 to 40 mph, G 70 mph in the afternoon
Snowfall expected in the next 24 hours: 0 - 1 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
Today, increasing cloud cover, becoming partly cloudy in the afternoon. Daytime highs 38 to 43 degrees F. West winds at 10 to 20 mph, increasing to 15 to 20 mph with gusts to 40 mph in the afternoon. Tonight, mostly cloudy skies with a slight chance of snow showers. Lows 23 to 28 degrees F. Southwest winds 15 to 30 mph, gusting to 45 mph. Wednesday, cloudy skies with a chance of snow. Daytime highs 31 to 36 degrees F. Southwest winds at 20 to 35 mph, gusting to 50 mph are expected.

Above 8000 Feet
Today, increasing cloud cover, becoming partly cloudy in the afternoon. Daytime highs 33 to 38 degrees F. West winds at 20 to 30 mph, gusting to 50 mph. Winds are expected to increase to 25 to 35 mph, gusting to 70 mph in the afternoon. Tonight, mostly cloudy skies with a slight chance of snow. Lows 20 to 25 degrees F. Southwest winds at 25 to 40 mph, gusting to 80 mph. Wednesday, cloudy skies with a chance of snow. Daytime highs 29 to 34 degrees F. Southwest winds at 30 to 45 mph with gusts to 90 mph are expected.

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.