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, April 4th, 2007 at 7:00 am

The bottom line: This morning, avalanche danger is LOW for all elevations and aspects. As daytime warming occurs, avalanche danger will rise to MODERATE above 8,000' on sun exposed E-SE-S-SW aspects 35 degrees and steeper. Below 8,000', avalanche danger will rise to MODERATE on all snow covered aspects, 35 degrees and steeper.

The broken, thin clouds persisted through overnight. A low pressure system moving into southern California should allow some clouds to remain in the area today. The ridge that is sitting over the forecast area should weaken some as this low moves in, then regain strength as the low passes to the east. The clouds should follow the low out of the area bringing a return to sunny skies and above normal temperatures for the rest of the week. Winds should continue to shift as the low to the south exerts some influence on the weather. Today they should continue to be out of the southwest and start shifting to the east tonight and back to the southwest tomorrow.

After climbing into the 50's at upper elevations yesterday the air temperatures stayed well above freezing at all elevations throughout the forecast area last night. Even though there was slightly more cloud cover last night, the clouds remained broken and thin for the most part. This lack of thick cloud cover should still have allowed for radiational cooling to refreeze the snow surface. The refreeze should be weaker than it has been over the last few days due to more cloud cover and higher temperatures. This weaker refreeze means that the snowpack should soften more and faster today in areas where the snowpack is exposed to the sun. In areas where the cloud cover persists this melting should take slightly longer. This melting will create free water in the snowpack that will weaken the snowpack and create areas of wet snow instability.

Snow surface conditions vary widely from rough and bumpy to smooth and enjoyable. The warm, sunny weather has caused daily melt-freeze cycles to occur in most of the forecast area. The only areas that are still holding on to winter are northerly aspects above 10,000'. Many northerly aspects above 9,000' have not undergone enough melt-freeze cycles for the snow from the last storm to become high quality corn snow. In these areas only a thin melt-freeze crust exists on the snow surface. Below 9,000', excellent corn snow conditions can be found mid morning in many areas, especially on E and SE aspects.

Any avalanche activity is unlikely prior to mid morning. As daytime warming occurs, areas of wet snow instability will form on steep slopes, in a variety of areas. Human triggered avalanches will become possible above 8,000' on E-SE-S-SW aspects, 35 degrees and steeper. Below 8,000', human triggered avalanches will become possible on all snow covered aspects, 35 degrees and steeper.

Keep in mind that when boot penetration in wet snow exceeds boot top height, human triggered wet snow avalanches are possible in that area. Step off of your equipment on a regular basis to check boot penetration. When evidence of wet snow instability such as deep boot penetration or pinwheels larger than 1 foot in diameter develop, move to a less sun exposed aspect or call it a day.

The bottom line: This morning, avalanche danger is LOW for all elevations and aspects. As daytime warming occurs, avalanche danger will rise to MODERATE above 8,000' on sun exposed E-SE-S-SW aspects 35 degrees and steeper. Below 8,000', avalanche danger will rise to MODERATE on all snow covered aspects, 35 degrees and steeper.

The Heavenly Ski Patrol has been generous enough to include the Sierra Avalanche Center as one of the benefactors of their annual fundraising party this year. The party is this Friday, April 6th at the Horizon Casino Resort in South Lake Tahoe from 7pm to midnight. Tickets are $10 at the door. A portion of the proceeds will go to the SAC operating budget for next season. For more information please click here. We will also raffle off a BCA backpack, beacon, shovel, and probe package on April 17th as a way to say thanks to everyone who has sent us a donation in the mail or via Pay Pal this season. All individuals who have donated $10 or more to SAC are automatically entered in this raffle. Thanks to all of our sponsors, the ski days, and everyone who has donated funding this winter, we have met our operating budget for this season and have a start on next year's funding. For more details about our financial situation please click here.

Andy Anderson , Avalanche Forecaster
Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
38 deg. F
Max. temperature at Sierra Crest past 24 hours:
52 deg. F
Average wind direction at Sierra Crest past 24 hours:
Southwesterly
Average wind speed at Sierra Crest past 24 hours:
20 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:
59 inches
Mountain Weather Forecast For Today:
Partly cloudy skies.
Temperature forecast for 8,000 to 9,000 feet:
46-50 degrees F.
Ridgetop winds forecast for the Sierra Crest:
Southwesterly at 15 to 20 mph with gusts to 30 mph
Snowfall expected in the next 24 hours:
0 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet:
Partly cloudy skies with daytime highs 48 to 54 degrees F. Southwest winds at 10 to 15 mph. Tonight, partly cloudy skies with overnight lows 36 to 40 degrees F. Southwest winds at 10 to 15 mph shifting to the northeast late tonight. Thursday, mostly sunny skies with daytime highs 48 to 52 degrees F. Northeast winds shifting to the southwest at 10 to 15 mph by the afternoon are expected.

Above 8000 Feet:
Partly cloudy skies with daytime highs 46 to 50 degrees F. Southwest winds at 15 to 20 mph with gusts to 30 mph. Tonight, partly cloudy skies with overnight lows 34 to 38 degrees F. Southwest winds at 15 to 20 mph with gusts to 30 mph shifting to the northeast late tonight. Thursday, mostly sunny skies with daytime highs 42 to 50 degrees F. Northeast winds shifting to the southwest at 15 to 20 mph by the afternoon 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.