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 Friday, March 16th, 2007 at 6:35 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.

High pressure will continue to dominate the forecast area through Sunday. Warm maximum daytime air temperatures are expected to peak today before a very gradual cooling trend begins on Saturday. Ridgetop winds shifted to southwesterly overnight and have remained light this morning. The next opportunity for precipitation to impact the forecast area is currently expected to occur late Monday.

Last night marked the sixth 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, before turning to mush and becoming unsupportive of the weight of a person 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 is believed to exist within the deeper snowpack at this time. However, some concern exists for free water percolation to create instability within faceted layers deep in the snowpack as warming continues. This would create the possibility of very hard to predict deep wet slab instability. Warming instability that does occur today is expected to be limited to human triggering of wet surface snow.

The surface snow has made to transition from wet new snow crystals to true corn snow in many sun exposed areas. As a result, roller ball and pinwheel activity have decreased, but still occur during the afternoon hours in 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, but not impossible.

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

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 46 deg. F
Max. temperature at Sierra Crest past 24 hours: 59 deg. F
Average wind direction at Sierra Crest past 24 hours: Easterly shifting to southwesterly overnight
Average wind speed at Sierra Crest past 24 hours: 20 mph
Maximum wind gust at Sierra Crest past 24 hours: 34 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 74 inches

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Mountain Weather Forecast For Today:
Sunny skies
Temperature forecast for 8,000 to 9,000 feet: 53 to 58 degrees F.
Ridgetop winds forecast for the Sierra Crest: Southwesterly 10-20 mph.
Snowfall expected in the next 24 hours: 0 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet:
Today, sunny skies with daytime highs 56 to 61 degrees F. Southwest winds at 5 to 15 mph. Tonight, clear skies with overnight lows 35 to 43 degrees F. Southwest winds at 5 to 15 mph. Saturday, sunny skies with daytime highs 54 to 59 degrees F. Southwest winds at 5 to 15 mph are expected.

Above 8000 Feet:
Today, sunny skies with daytime highs 53 to 58 degrees F. Southwest winds at 10 to 20 mph. Tonight, clear skies with overnight lows 35 to 45 degrees F. Southwest winds at 10 to 20 mph. Saturday, sunny skies with daytime highs 50 to 55 degrees F. Southwest winds at 10 to 20 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:
	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.