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 Sunday, February 11th, 2007 at 7:00 am

The bottom line: Near and above treeline, avalanche danger is CONSIDERABLE. Human triggered avalanches are probable 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 is MODERATE.

There are several small disturbances approaching the area in the wake of the large subtropical moisture train that rolled through over the last few days. The first of these will bring up to 8 more inches of snow to the area today. Luckily the temperatures are also cooling off, and snow levels have dropped to lake level. This makes last night's and today's snow a little less dense than the snow of the last few days. The southwest winds increased yesterday afternoon and are forecasted to remain in the 35-45 mph range at the ridgetops today. As these smaller disturbances roll through southwest flow is forecasted to continue but with less intensity. The ridgetop winds should begin to calm down tonight.

We received about 8 inches of new snow overnight bringing the storm totals to 26-36 inches of snow over the last several days. There is still plenty of snow available for wind transport and the wind continues to blow. Windslabs and large cornices will to continue to form today on the NW-N-NE-E aspects. The wet, dense snow that fell through out most of the storm is bonding well to the old snow surfaces and consolidating relatively quickly. The new snow from last night and today will be colder and less dense and seems to be bonding less quickly. This new snow is forming reactive windslabs on top of the wet dense snow from earlier in the storm. The winds will continue to transport snow throughout the day causing these slabs to become larger and more widespread. Human triggering of these slabs is probable, and we may even see some natural avalanches occurring on the most heavily wind loaded slopes today. Watch out for any wind loaded terrain. You can use clues like cornices, blowing snow, drifted snow, ripples, and other wind created features to help you recognize wind loaded slopes. Most of the avalanche activity today will probably occur within the new snow on weaknesses that formed during the storm as the weather conditions changed slightly. As the day continues and we get more wind loading the avalanche danger will become more widespread and avalanches will likely become larger. Be careful out there and choose your terrain wisely.

Yesterday slab avalanches up to 3 ft in depth were reported on NW-N-NE wind loaded slopes. Several of these avalanches released naturally in the morning while others were explosive triggered. Ski-cuts triggered several smaller avalanches (R1-D2) through out the day. Some skier triggered wet snow sluffs on slopes steeper than 35 degrees below 8000' were also observed.

The bottom line: Near and above treeline, avalanche danger is CONSIDERABLE. Human triggered avalanches are probable 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 is MODERATE.

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Andy Anderson, Avalanche Forecaster
Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
26 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:
45 mph
Maximum wind gust at Sierra Crest past 24 hours:
85 mph
New snow fall at 8,200 feet past 24 hours:
12 inches
Total snow depth at 8,200 feet:
58 inches
Mountain Weather Forecast For Today:
Snow decreasing in intensity by mid morning. Accumulation of up to 8 ".
Temperature forecast for 8,000 to 9,000 feet:
23-28 deg. F
Ridgetop winds forecast for the Sierra Crest:
Southwesterly 35 - 45 mph, gusting to 60 mph
Snowfall expected in the next 24 hours:
8 inches
2 Day Mountain Weather Forecast:

7000 to 8000 Feet
Snow decreasing in intensity by midday. Accumulations of up to 6 inches. Southwest winds at 10 to 20 mph with gusts to 30 mph. Daytime highs 26 to 31 degrees F. Tonight, mostly cloudy with a chance of snow. Lows 18 to 23 degrees F. Southwest winds at 10 to 20 mph. Tomorrow, mostly cloudy with a slight chance of snow. Southwest winds at 10 to 20 mph. Daytime highs 25 to 30 degrees F.

Above 8000 Feet
Snow decreasing in intensity by midday. Accumulations of 4 to 8 inches. Southwest winds at 35 to 45 mph with gusts to 60 mph. Daytime highs 23 to 28 degrees F. Tonight, mostly cloudy with a chance of snow. Lows 15 to 20 degrees F. Southwest winds at 20 to 30 mph with gusts to 60 mph. Tomorrow, mostly cloudy with a slight chance of snow. Southwest winds at 10 to 15 mph with gusts to 25. Daytime highs 25 to 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:
	Sunday:	Sunday Night:	Monday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Sunday:	Sunday Night:	Monday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.