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 27th, 2007 at 7:01 am

The bottom line: This morning, avalanche danger near and above treeline is HIGH on wind loaded NW-N-NE-E-SE aspects 32 degrees and steeper. The avalanche danger is CONSIDERABLE below treeline in open areas 35 degrees and steeper.

This storm is starting to abate. Snowfall started tapering off early this morning and should be less intense today. This evening another small storm should move through the area with much less wind and accumulation. Over the next few days a high pressure system should start to build over the area bringing clearer weather. The ridgetop winds should begin to calm down some today and shift more to the west over the next few days.

In the last 24 hrs the forecast area has received 18-20 inches of new snow. This accumulation brings storm totals to 48-56 inches of new snow in the last few days. Several different storm snow weakness ranging from graupel to density inversions (more dense on top of less dense) have been created in the storm snow. Tests on these weakness continue to fail with moderate force. It will take some time before these weakness in the storm snow consolidate.

The winds have consistently been in the 50 to 60 mph range with ridgetop gusts reaching well over 100 mph almost every hour throughout the storm. They have built large, reactive windslabs on the leeward slopes. The new snow that accumulated in the last 24hrs will continue to provide ample material for the wind to transport. With the winds expected to remain in 30-40 mph range above treeline today, significant wind loading will continue to occur. This new loading will cause the windslabs that have already formed throughout the storm to continue to grow all dimensions: depth, width, and extent down slope.

Above treeline human triggered avalanches are likely in wind loaded areas on NW-N-NE-E-SE aspects, 32 degrees and steeper. Natural avalanches are likely in this same terrain on slopes 35 degrees and steeper again today. Many of the avalanches that occur today could be large, encompass the full start zone, and run full path. Most of these slides should occur due to failures of the weaknesses in the storm snow.

Human triggered and natural avalanche activity was reported yesterday throughout the forecast area. Many avalanches occurred in response to ski cutting. Most of these slides occurred due to failures of weakness in the storm snow. Both natural and human triggered avalanche activity was observed across the entire width of most avalanche start zones and some of the slides ran close to full path. Crown depths between 1 and 3 feet deep were observed.

The bottom line: This morning, avalanche danger near and above treeline is HIGH on wind loaded NW-N-NE-E-SE aspects 32 degrees and steeper. The avalanche danger is CONSIDERABLE below treeline in open areas 35 degrees and steeper.

At this time, we are still short $5,000 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.

Andy Anderson , Avalanche Forecaster
Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
10 deg. F
Max. temperature at Sierra Crest past 24 hours:
22 deg. F
Average wind direction at Sierra Crest past 24 hours:
Westsouthwesterly
Average wind speed at Sierra Crest past 24 hours:
55 mph
Maximum wind gust at Sierra Crest past 24 hours:
143 mph
New snow fall at 8,200 feet past 24 hours:
15-20 inches
Total snow depth at 8,200 feet:
107 inches
Mountain Weather Forecast For Today:
Light snow showers this morning becoming heavier this afternoon and evening.
Temperature forecast for 8,000 to 9,000 feet:
13 to 19 degrees F.
Ridgetop winds forecast for the Sierra Crest:
West 30-40 mph, gusting to 75 mph.
Snowfall expected in the next 24 hours:
8-15 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet
Today, occasional snow showers with accumulations of 2-4 inches. Wind should continue to be from the southwest but with slightly decreased intensity to 15-25 mph with gusts to 40 mph. Daytime highs 21 to 27 degrees F. Tonight, cloudy with an increase in snowfall. Snow accumulation 5 to 10 inches. Southwest winds 15 to 25 mph with gusts to 35 mph. Overnight lows around 9 degrees F. Wednesday, cloudy with scattered snow showers. Snow accumulation 3 to 6 inches. West winds at 20 to 30 mph are expected. Daytime highs 19 to 27 degrees F.

Above 8000 Feet
Today, occasional snow showers with accumulations of 2-5 inches. Winds should be from the west but with slightly decreased intensity to 30-40 mph with gusts to 75 mph. Daytime highs 13 to 19 degrees F. Tonight, cloudy with an increase in snowfall. Snow accumulation 6 to 10 inches. Southwest winds 30 to 40 mph with gusts to 60 mph. Overnight lows 4 to 10 degrees F. Wednesday, cloudy with scattered snow showers. Snow accumulation 4 to 8 inches. West winds at 25 to 35 mph are expected. Daytime highs 12 to 18 degrees F.

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.