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, February 9th, 2007 at 7:00 am

The bottom line: Near and above treeline, avalanche danger is CONSIDERABLE. Human triggered avalanches with crowns of 1-3 ft are likely and natural avalanche activity is possible today. Avalanche activity is most likely on wind loaded NW-N-NE-E aspects 32 degrees and steeper. Below treeline, avalanche danger in CONSIDERABLE above 7,000'. Below 7800' avalanche activity is likely due to rapid warming and rain on new snow.

The current storm system is bringing moisture and slightly warmer temperatures to the area. Last night we received between 6 and 9 inches of snow above 7000' and rain below that. The snow is expected to continue through Saturday night and into Sunday. For today and tomorrow snow levels should hover between 7000' and 7500'. The snow level is predicted to drop on Sunday. During the day today up to 8 inches of snow is expected to accumulate above 8000' with another 6 inches falling between 7000' and 8000'. Southwesterly ridgetop winds are expected to remain in the 30 to 40 mph range today, which will provide ideal conditions for building cornices and wind loading many of our avalanche starting zones. As the storm continues overnight tonight we may wake up to another 2 to 4 inches of new snow by Saturday morning.

Above 7500' 6 to 9 inches of new 13-15% density snow fell overnight and accumulated on the new less dense snow from yesterday. The winds have been consistent out of the southwest at 30-40 mph throughout the storm. These winds created windslabs on the NW-N-NE-E aspects yesterday and those slabs continued to grow overnight. As it continues to blow and snow today we should see these windslabs become increasingly reactive. Human triggering of these slabs is likely and we may even see some natural avalanches occurring on the most heavily wind loaded slopes today. Most of the avalanche activity today will probably occur within the new snow at the interface between yesterday's lighter snow and last night's heavier snow or at the new/old snow interface creating slabs of 1-3 ft in depth. In the Mt. Rose area it is possible that avalanches could step down into the older weak layers. The other avalanche concern for today is the rising freezing levels and rain. This rapid warming and rain on new snow could easily destabilize the new snow and allow avalanche activity to occur below 7800' today. As the day continues and we get more snow the avalanche danger will become more widespread and avalanches will likely become larger. Be careful out there and choose your terrain wisely.

Yesterday small avalanches up to 1 ft in depth and 70-100 ft wide were reported on northerly wind loaded slopes. These avalanches were triggered by cornices collapsing onto the slopes. Observers also reported some shooting cracks on windloaded slopes near and above treeline.

The bottom line: Near and above treeline, avalanche danger is CONSIDERABLE. Human triggered avalanches with crowns of 1-3 ft are likely and natural avalanche activity is possible today. Avalanche activity is most likely on wind loaded NW-N-NE-E aspects 32 degrees and steeper. Below treeline, avalanche danger in CONSIDERABLE above 7,000'. Below 7800' avalanche activity is likely due to rapid warming and rain on new snow.

With the return of precipitation to the forecast area, we will resume posting advisories each morning, prior to 7am.

At this time, we have not raised enough money to meet our operating budget for this year. If you use this service with any regularity and would like to continue to do so, please show your 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. We updated the financial graph with the current fund-raising numbers for more details, click 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):
29 deg. F
Max. temperature at Sierra Crest past 24 hours:
32 deg. F
Average wind direction at Sierra Crest past 24 hours:
southwesterly
Average wind speed at Sierra Crest past 24 hours:
30 mph
Maximum wind gust at Sierra Crest past 24 hours:
73 mph
New snow fall at 8,200 feet past 24 hours:
6-9 inches
Total snow depth at 8,200 feet:
39 inches
Mountain Weather Forecast For Today:
Snow with accumulation of up to 8".
Temperature forecast for 8,000 to 9,000 feet:
30 deg. F
Ridgetop winds forecast for the Sierra Crest:
Southwesterly 30 - 40 mph, gusting to 75 mph
Snowfall expected in the next 24 hours:
8 - 12 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet
Snow with accumulations of up to 6". Snow level 7000' to 7500'. Southwest winds at 10 to 20 mph, gusting to 35 mph. Daytime highs 32 to 37 degrees F. Tonight, cloudy skies with snow. Snow accumulation 2 inches. Lows 30 to 35 degrees F. Southwest winds at 10 to 15 mph with gusts to 25. Tomorrow, snow with accumulations of up to 6". Snow level 7000' to 7500'. Southwest winds at 10 to 20 mph. Daytime highs 32 to 37 degrees F.

Above 8000 Feet
Snow with accumulations of up to 8 ". Southwest winds at 30 to 40 mph, gusting to 75 mph. Daytime highs around 30 degrees F. Tonight, cloudy skies with snow. Snow accumulation 2-4 inches. Lows 23 to 29 degrees F. Southwest winds at 20 to 30 mph with gusts to 40. Tomorrow, snow with accumulations of up to 8 ". Southwest winds at 30 to 40 mph with gusts to 70. Daytime highs around 30 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:
	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.