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 Wednesday, March 14th, 2007 at 6:55 am

The bottom line: This morning, avalanche danger is LOW for all aspects and elevations. As daytime warming occurs, avalanche danger will increase to MODERATE on sun exposed E-SE-S-SW aspects 35 degrees and steeper at all elevations.

A weak weather system is passing to the north of the forecast area. This system will bring a weak cold front through the forecast area today. Thin high cloud cover and maximum daytime air temperatures 3-7 degrees F. cooler than yesterday are expected. Ridgetop winds have remained light to moderate westerly overnight. The current ridgetop wind gusts are expected increase slightly this morning before returning to light to moderate and continuing through this evening. Another significant warming trend in expected for Friday and Saturday.

Last night marked the fourth night in a row of continuous above freezing air temperatures. Radiational cooling of the snowpack is causing the snow surface to refreeze overnight, leaving wet unfrozen snow below 3-4 inches of melt-freeze crust at the surface. This crust will remain supportable for several hours this morning, turning to mush around mid day.

The snowpack has undergone enough melt-freeze cycles to create uniform, isothermal snow within the top 2-3 feet of the snowpack. Layers deeper within the snowpack are well rounded. Existing faceted layers are also becoming increasingly rounded and well bonded. Overall good stability exists within the deeper snowpack. Any warming instability that occurs today will be limited to the wet upper snowpack.

The surface snow has made to transition from wet new snow crystals to more true corn snow in many sun exposed areas. As a result, roller ball and pinwheel activity have decreased, but are still visible during the afternoon hours is response to human triggers. Pay attention to signs of surface instability. Step off of your equipment and check boot penetration as daytime warming occurs. Avoid steep slopes where boot penetration exceeds boot top height. Human triggered wet snow avalanche activity will become possible today as daytime warming occurs. Natural wet snow avalanche activity is unlikely.

The bottom line: This morning, avalanche danger is LOW for all aspects and elevations. As daytime warming occurs, avalanche danger will increase to MODERATE on sun exposed E-SE-S-SW aspects 35 degrees and steeper at all elevations.

Our next fundraiser will occur on March 25th at Sugar Bowl Ski Area. For more information, click here or visit our homepage by clicking on the toolbar up top. At this time, we are still short $2,000 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 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

--------------------------------------------------------------------------------

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 36 deg. F
Max. temperature at Sierra Crest past 24 hours: 52 deg. F
Average wind direction at Sierra Crest past 24 hours: Westerly
Average wind speed at Sierra Crest past 24 hours: 25 mph
Maximum wind gust at Sierra Crest past 24 hours: 40 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 79 inches

--------------------------------------------------------------------------------
Mountain Weather Forecast For Today:
Mostly sunny skies
Temperature forecast for 8,000 to 9,000 feet: 43 to 48 degrees F.
Ridgetop winds forecast for the Sierra Crest: Westerly 20-30 mph with gusts to 60 mph this morning.
Snowfall expected in the next 24 hours: 0 inches

--------------------------------------------------------------------------------
2 Day Mountain Weather Forecast:
7000 to 8000 Feet

Today, mostly sunny with daytime highs 48 to 53 degrees F. West winds at 15 to 20 mph with gusts to 30 mph. Tonight, clear skies with overnight lows 32 to 37 degrees F. West winds at 10 to 20 mph with gusts to 30 mph in the evening. Winds shifting to light northeast around midnight. Thursday, sunny skies with daytime highs 51 to 56 degrees F. East winds at 5 to 10 mph are expected.

Above 8000 Feet

Today, mostly sunny with daytime highs 43 to 48 degrees F. West winds at 20 to 30 mph with gusts to 60 mph in the morning. Wind gusts decreasing to 40 mph in the afternoon. Tonight, clear skies with overnight lows 34 to 39 degrees F. West winds at 15 to 25 mph with gusts to 30 mph in the evening. Thursday, sunny skies with daytime highs 46 to 51 degrees F. East winds at 10 to 15 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:
	Wednesday:	Wednesday Night:	Thursday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.